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Revision 01: January, 2010

This document is intended as a guideline for success

assessed based on lab work submitted in a report or other format. They are: DESIGN, DATA COLLECTION

AND PROCESSING, and CONCLUSION AND EVALUATION.

combined with the writing for the IB criteria, comprise a complete lab report document.

The writing of a lab report is an important part of science. The purpose of a lab report is present, analyze,

discuss and evaluate the data obtained during the laboratory investigatio

report serves to convey information in a concise manner to members of the scientific community. In one

word, your report COMMUNICATES to the rest of the world.

“It is important to keep the target audience in mind whe

good idea would be to imagine writing the report for a teacher who has not taken a

science course since high school. Write to an adult audience and recognize the

importance of explaining and presenting the findings clearly so th

may not be a science teacher) can understand and learn from the report.

A typical lab report can be broken up into several major sections:

• Title

• Abstract

• Introduction (includes

identifies variables and

• Apparatus (or Materials)

• Method (or Procedure)

• Results (or Data Collection)

• Analysis

• Discussion (includes conclusions and evaluation)

• References

• Appendix

It is unrealistic to write complete reports for each

be required to complete reports containing only some of these sections. Pay attention to lab reporting

requirements given in the laboratory activity outline.

TITLE (does not need to be a separate

The title is neat, professional and includes the following information:

1. title of report

• describes the experiment ex. “

Volume of a Gas” is better than just “

2. your name

3. your partner’s name (if applicable)

4. the date the lab investigation was completed

Writing a Full Lab Report

General Information

This document is intended as a guideline for success in IB Sciences internal assessment. Three criteria are


AND PROCESSING, and CONCLUSION AND EVALUATION. This document focuses on the “extras” that when

writing for the IB criteria, comprise a complete lab report document.


discuss and evaluate the data obtained during the laboratory investigation. Like a scientific paper, the lab


word, your report COMMUNICATES to the rest of the world.

It is important to keep the target audience in mind when writing a lab report. A



importance of explaining and presenting the findings clearly so that the reader (who

may not be a science teacher) can understand and learn from the report.

A typical lab report can be broken up into several major sections:

Introduction (includes background information, the investigative question

variables and states a hypothesis)

Apparatus (or Materials)

Method (or Procedure)

Results (or Data Collection)

Discussion (includes conclusions and evaluation)

References

It is unrealistic to write complete reports for each investigation conducted. It is more likely that you will


requirements given in the laboratory activity outline.

(does not need to be a separate page)

The title is neat, professional and includes the following information:

describes the experiment ex. “Charles’s Law - The Effect of Changing Temperature on the

is better than just “Charles’s Law”

(if applicable)

the date the lab investigation was completed

Student Guide


General Information

internal assessment. Three criteria are


This document focuses on the “extras” that when


n. Like a scientific paper, the lab


n writing a lab report. A



at the reader (who

may not be a science teacher) can understand and learn from the report.”

background information, the investigative question,

investigation conducted. It is more likely that you will


The Effect of Changing Temperature on the

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ABSTRACT

An abstract is the first section of scientific papers published in most journals. The purpose of the abstract

is to provide the reader with a summary of the study outli

useful for a student doing research on a related topic and looking for useful information. Abstracts for

proper scientific papers can be quite long but usually run about 250 words. Your abstracts will be sh

and include the following information:

1. an outline of the scientific concept being tested and the experiment purpose

2. a brief statement of how the concept is being tested

3. a summary of the results

If you are having difficulty writing an abstract, it

findings of the activity you have just completed.

Abstracts can be as little as three sentences long. A sample abstract (very short) may read as follows:

Charles’s Law states that the volume of a fixed quantity of gas at constant pressure is

known to change proportionally with temperature. This experiment investigates

this relationship by varying the temperature of fixed mass of g

measuring the volume. The data obtained was consistent with the linear

relationship defined by Charles’s Law.

INTRODUCTION

The introduction is divided into a number of sections:

Background Information

• This section provides a review of the knowledge in the field of the experiment. For this you

will have to do some background research to find theory or concept information relating to

the lab. Sources of background information must be referenced and cite

appropriate format (see reference section).

• REMINDER – quality (being concise) is better than quantity (being long winded). Keep

background information relevant to the lab at hand.

terms; rather write as though

• It is absolutely critical you understand the basics of the science behind your experiment. To

obtain full marks under the Conclusion and Evaluation criterion, the results obtained must

be discussed in relation to the theory.

Purpose/Objective/Investigative Question

• State clearly and concisely the research question. Using

it easy for the reader to instantly see what you are trying to accomplish.

• Stating the research question is evaluated under Aspect 1 of the Design criterion

Hypothesis

• A proper hypothesis must be directly related to the research question and explained. The

hypothesis does not need to be validated

• Use your background informatio

explanation. For example

dry air is expected to increase proportionally as per Charles’ Law (V

Concept being

investigated


General Information


is to provide the reader with a summary of the study outlined in the journal article. This is especially


proper scientific papers can be quite long but usually run about 250 words. Your abstracts will be sh

and include the following information:

an outline of the scientific concept being tested and the experiment purpose

a brief statement of how the concept is being tested

If you are having difficulty writing an abstract, it is unlikely that you clearly understood the purpose and

findings of the activity you have just completed.




this relationship by varying the temperature of fixed mass of gas and then

measuring the volume. The data obtained was consistent with the linear

relationship defined by Charles’s Law.

The introduction is divided into a number of sections:

This section provides a review of the knowledge in the field of the experiment. For this you


Sources of background information must be referenced and cited using

appropriate format (see reference section).

quality (being concise) is better than quantity (being long winded). Keep

background information relevant to the lab at hand. DO NOT present a “list” of defined

terms; rather write as though it was a textbook explanation of the concepts involved.

It is absolutely critical you understand the basics of the science behind your experiment. To


n relation to the theory.

/Investigative Question

State clearly and concisely the research question. Using boldface type is a great way to make

it easy for the reader to instantly see what you are trying to accomplish.

ch question is evaluated under Aspect 1 of the Design criterion

A proper hypothesis must be directly related to the research question and explained. The

hypothesis does not need to be validated by the experiment.

Use your background information to make an educated hypothesis and provide a simple

explanation. For example “ If the absolute temperature is increased then the volume of

dry air is expected to increase proportionally as per Charles’ Law (Vgas ∝∝∝∝

Result and

conclusion

Student Guide


General Information


ned in the journal article. This is especially


proper scientific papers can be quite long but usually run about 250 words. Your abstracts will be shorter

is unlikely that you clearly understood the purpose and




This section provides a review of the knowledge in the field of the experiment. For this you


d using

quality (being concise) is better than quantity (being long winded). Keep

present a “list” of defined

it was a textbook explanation of the concepts involved.

It is absolutely critical you understand the basics of the science behind your experiment. To


type is a great way to make

ch question is evaluated under Aspect 1 of the Design criterion

A proper hypothesis must be directly related to the research question and explained. The

n to make an educated hypothesis and provide a simple

“ If the absolute temperature is increased then the volume of

Tabs). This

Summary of

investigation

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result is expected because

kinetic energy and move faster thereby occupying more space.”

• The previous hypothesis makes a quantitative (numerical) prediction relating the two

variables. This helps when analyzing the data from the actual experiment. If a graph of the

two variables is linear then volume is proportional to absolute temperature a

hypothesis is valid. IT IS NOT ENOUGH TO SAY “as temperature increases, volume

increases”.

• This hypothesis presents an explanation that provides reasoning to back up the hypothesis

statement. This explanation need not be absolutely correct but it

Even if a hypothesis is not required for a particular assignment, thinking about what might

happen, using your subject area knowledge is very useful prior to the experiment. As you collect

data, you can compare what you are seeing to what you predicted. You will also be in a better

position to relate the theory to the result in the conclusion.

Variables

• Clearly identify variables including the

o independent variable (the one manipulated)

o dependent variable (the one affected)

o fixed or controlled variables (all other factors kept constant)

• State how you are manipulating/measuring/monitoring/controlling

• You must explicitly identify variables under Aspect 1 of the Design criterion.

• How variables are controlled/monitored is evaluated in Aspect 2 of the Design criterion.

MATERIALS/APPARATUS

• Provide a detailed list of all lab equipment and ma

material involved.

• A labeled diagram of the experiment setup can be referred to as part of the materials list.

• Don’t forget measuring tools. State precision and range of each.

• Use proper names for equipment.

PROCEDURE

The procedure outlines the method used to complete the experiment. Procedures do not just describe

experimental techniques. Procedures also:

• indicate where and how often data is collected

• are written to specifically address concerns about

• state the data processing and analysis requirements

Plan at least 7-10 manipulations of the independent variable, and also multiple trials (3

manipulation if appropriate. Collecting sufficient data is evalua

REMEMBER THIS – write the procedure with the intention that an average Grade 9 or 10 student could

collect the materials and perform the experiment with no other extra help.

RESULTS

This section contains observations and data collected during the course of the experiment. Such data is

called raw data and will consist of the measurements you made during the lab (make sure you make all

the appropriate measurements and enough of them).

Raw data must be presented neatly and in a format that is easy to understand. This will almost always

require a table. The presentation of raw data is evaluated under Aspect 1 of the Data Collection and

Processing criterion.


General Information

result is expected because as temperature increases, the air molecules will gain

kinetic energy and move faster thereby occupying more space.”

The previous hypothesis makes a quantitative (numerical) prediction relating the two


two variables is linear then volume is proportional to absolute temperature and the

IT IS NOT ENOUGH TO SAY “as temperature increases, volume

This hypothesis presents an explanation that provides reasoning to back up the hypothesis

statement. This explanation need not be absolutely correct but it should be scientific.


using your subject area knowledge is very useful prior to the experiment. As you collect


position to relate the theory to the result in the conclusion.

identify variables including the

independent variable (the one manipulated)

dependent variable (the one affected)

fixed or controlled variables (all other factors kept constant)

State how you are manipulating/measuring/monitoring/controlling the variables.

You must explicitly identify variables under Aspect 1 of the Design criterion.

How variables are controlled/monitored is evaluated in Aspect 2 of the Design criterion.

Provide a detailed list of all lab equipment and materials used. Include quantities of each

A labeled diagram of the experiment setup can be referred to as part of the materials list.

Don’t forget measuring tools. State precision and range of each.

Use proper names for equipment.



indicate where and how often data is collected

are written to specifically address concerns about conducting a controlled experiment

state the data processing and analysis requirements

10 manipulations of the independent variable, and also multiple trials (3-5) of each

manipulation if appropriate. Collecting sufficient data is evaluated under Aspect 3 of the Design criterion.

write the procedure with the intention that an average Grade 9 or 10 student could

collect the materials and perform the experiment with no other extra help.

rvations and data collected during the course of the experiment. Such data is


the appropriate measurements and enough of them).

d neatly and in a format that is easy to understand. This will almost always

The presentation of raw data is evaluated under Aspect 1 of the Data Collection and

Student Guide


General Information

as temperature increases, the air molecules will gain

The previous hypothesis makes a quantitative (numerical) prediction relating the two


nd the

IT IS NOT ENOUGH TO SAY “as temperature increases, volume

This hypothesis presents an explanation that provides reasoning to back up the hypothesis

should be scientific.


using your subject area knowledge is very useful prior to the experiment. As you collect


the variables.

How variables are controlled/monitored is evaluated in Aspect 2 of the Design criterion.

terials used. Include quantities of each

A labeled diagram of the experiment setup can be referred to as part of the materials list.


conducting a controlled experiment

5) of each

ted under Aspect 3 of the Design criterion.

write the procedure with the intention that an average Grade 9 or 10 student could

rvations and data collected during the course of the experiment. Such data is


d neatly and in a format that is easy to understand. This will almost always

The presentation of raw data is evaluated under Aspect 1 of the Data Collection and

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ANALYSIS

Raw data is processed in the analysis sectio

calculated values obtained from raw data, averages, graphing raw data

plot, converting sketches to formal diagrams etc. The two most important considerations when

processing data are to a) perform calculations correctly and b) present results in an unambiguous

manner that is easy to interpret.

Performing calculations completely and correctly is evaluated under Aspect 2 of Data Collection and

Processing. Presentation of processed data, sample calculations and the propagation of uncertainty is

evaluated by Aspect 3.

CONCLUSION

This section begins with a statement of results, an explanation and conclusions. The conclusion should be

backed up with relevant information and a statement of validity for the experimental result. This may

mean doing some research in order to compare an experimentally determined value with an accepted

value from the literature.

The conclusion can be simply broken into three

• A knowledge claim

• Evidence to support the knowledge claim

• Comparing the knowledge claim to others

investigation)

The conclusion is graded under Aspect 1 of the Conclusion and Evaluation

EVALUATION

Evaluation of the lab is one of the more difficult parts. Students must critically examine the entire lab

process including the procedure, the equipment used, how the lab was conducted and how the data was

analyzed in an attempt to identify significant limitations, weaknesses or errors. Furthermore, you are

expected to provide realistic suggestions to improve where fault has been identified.

REFERENCES and BIBLIOGRAPHY

• During background research, you may consult a number of sou

report. All sources of information must be credited in the lab report.

• If you directly refer to information from other literature (a quote, a definition, an accepted physical

constant, other similar research) then a

following the information. The reference is placed in parentheses and includes the author’s last name

and the publication date. Details of the source literature are included in the Bibliography.

example:

Temperature is defined as “the average kinetic energy of all matter making up a

substance” (Kaboom, 1967)

• General information found in many books does not have to be directly referenced in text but the

source must be included in the Bibliogra

• there are numerous formats for references, use the format presented in your student handbook.


General Information

Raw data is processed in the analysis section with the results presented. Data processing includes any

calculated values obtained from raw data, averages, graphing raw data and transforming to get a linear

, converting sketches to formal diagrams etc. The two most important considerations when



Presentation of processed data, sample calculations and the propagation of uncertainty is


ant information and a statement of validity for the experimental result. This may


The conclusion can be simply broken into three parts:

Evidence to support the knowledge claim (from the data)

Comparing the knowledge claim to others (literature value and the science behind the

The conclusion is graded under Aspect 1 of the Conclusion and Evaluation criterion.



o identify significant limitations, weaknesses or errors. Furthermore, you are

expected to provide realistic suggestions to improve where fault has been identified.

During background research, you may consult a number of sources of information relevant to the lab

report. All sources of information must be credited in the lab report.

If you directly refer to information from other literature (a quote, a definition, an accepted physical

constant, other similar research) then a direct reference must be placed in the text of your report


and the publication date. Details of the source literature are included in the Bibliography.


substance” (Kaboom, 1967)

General information found in many books does not have to be directly referenced in text but the

source must be included in the Bibliography.

there are numerous formats for references, use the format presented in your student handbook.

Student Guide


General Information

Data processing includes any

and transforming to get a linear

, converting sketches to formal diagrams etc. The two most important considerations when



Presentation of processed data, sample calculations and the propagation of uncertainty is


ant information and a statement of validity for the experimental result. This may


(literature value and the science behind the



o identify significant limitations, weaknesses or errors. Furthermore, you are

rces of information relevant to the lab

If you directly refer to information from other literature (a quote, a definition, an accepted physical

direct reference must be placed in the text of your report


and the publication date. Details of the source literature are included in the Bibliography. For


General information found in many books does not have to be directly referenced in text but the

there are numerous formats for references, use the format presented in your student handbook.

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APPENDICES

The appendices contain a number of items that could not or should not have been included in the main

body of the report. This includes

• raw data not presented in the report, ticker tapes etc

• experiment procedures (reference source)

• rough data and calculations

• other relevant information

Note that the appendix is not extra work, it is just work you usually do but presented in a different

section. Presentation is important in this section just like any others. Present neatly, and clearly

and follow guidelines for tables etc.

OVERALL

In general (getting those additional marks)

• be neat, professional presentation impresses

• learn to use your word processor (subscripts, symbols, tables)

• write in proper form (use paragraphs to separate different ideas)

• write in passive voice (no I, we etc)

• proof read for spelling and grammar mistakes, write clearly and concisely, make sure it flows in a

logical manner.

REVIEW THIS GUIDE REGULARLY AND ESTABLISH A PERSONAL CHECKLIST THAT YOU GO THROUGH

WHEN WRITING ANY REPORT. EVALUATE YOUR CHECKLIST TO ENSURE YOU DO NOT MAKE THE

SAME MISTAKES OVER AND OVER.


General Information


data not presented in the report, ticker tapes etc

experiment procedures (reference source)

rough data and calculations

other relevant information


on. Presentation is important in this section just like any others. Present neatly, and clearly

and follow guidelines for tables etc.

In general (getting those additional marks)

be neat, professional presentation impresses

processor (subscripts, symbols, tables)

write in proper form (use paragraphs to separate different ideas)

write in passive voice (no I, we etc)

proof read for spelling and grammar mistakes, write clearly and concisely, make sure it flows in a



Student Guide


General Information



on. Presentation is important in this section just like any others. Present neatly, and clearly

proof read for spelling and grammar mistakes, write clearly and concisely, make sure it flows in a



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Revision 02: September, 2009

Student Guide

Internal Assessment for Group 4

Criterion: DESIGN

This document is intended as a guideline for success in IB Sciences internal assessment. Three criteria are


AND PROCESSING, and CONCLUSION AND EVALUATION. Each criterion is divided into three aspects which

are individually evaluated.

Design (D)

The IBO rubric for Design is shown below:

The Design criteria evaluate the student’s ability to independently plan a controlled scientific experiment.

Given a general topic, students are asked to define a focused research question and then plan a procedure

to collect data relevant to addressing the research question they have chosen.

Aspect 1 – Defining the problem and selecting variables

The Research Question

• A good research question is specific and usually relates two quantitative variables. For

example “What is the effect of increasing temperature on the volume of a fixed mass of

dry air?”

HINT: Keep it simple! – When deciding on an investigative question, think about how you are

going to MEASURE, (either directly or indirectly) both the dependent and independent variables.

This is a critical step in ensuring you will have sufficient data to process later on.

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Student Guide


Criterion: DESIGN

There are many examples of bad research questions!? Try not to write one of them.

1. Does increasing temperature increase gas volume?

(Research questions that can be answered yes/no are not scientific)

2. How does temperature affect volume?

(Not focused enough – volume of what?)

3. What is the effect of increasing temperature on the volume of a gas?

(better, but could be more specific – the gas being used is air, the mass is not changing)

Variables

• Relevant variables must be clearly identified

Hint: After defining the research question, devote the next section of your report to

variables. This list must include the

� independent variable (the factor manipulated)

� dependent variable (the responding variable)

� fixed or controlled variables (other relevant variables that could affect the

result)

One good way to present variables is in table format. This is covered in the next section.

• If we continue with the Charles’ Law example:

Independent variable : Absolute Temperature (Kelvin)

Dependent variable: Volume of air (cm3)

Controlled variables: Pressure, mass of air

Note: units of measurement were stated (optional) and the controlled variables include

any significant factors that could affect the result.

Summary of IB Evaluation Criterion: DESIGN

THIS IS YOUR CHECKLIST!

Aspect 1 –Defining Problem and Selecting Variables

This aspect evaluates the purpose/objective statement and the list of identified variables.

• The research question must be focused. Be specific, descriptive and detailed.

• The independent, dependent and controlled (constant) variables must be explicitly

identified. Limit the controlled variables to only those that are relevant (could reasonably

affect the outcome) and therefore should be monitored.

Aspect 2 – Controlling variables

How the control of variables is accomplished in the investigation plan can be presented in three different

areas when writing the lab report.

1. When variables are identified

When variables are identified (see previous section) a table format is suggested that in addition to

explicitly identifying variables, also states how the independent variable is manipulated, how the

dependent variable is measured and how the controlled variables are monitored and kept constant. For

example:

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Student Guide


Criterion: DESIGN

Variables Manipulated, Measured or Controlled by:

Independent Absolute temperature Varying from 273 K to 373 K using water bath

Dependent Volume of air Measured directly using syringe graduations

Controlled Pressure in gas syringe Allow time to reach equilibrium so pressure inside equals

atmospheric pressure. Monitor atmospheric pressure during

experiment to ensure consistency.

Mass of air Do not allow air to enter or leave syringe during experiment

Note:

Independent variable

When you are planning, think about the RANGE of manipulation for the independent variable. You should

attempt to have at least 8 to 10 manipulations over a range that will provide meaningful data.

Indirect measurement of variables

It may not be possible to measure a variable directly. For example, in an experiment relating temperature

(independent) to rate of reaction (dependent), the rate of reaction might be determined from other

measurements made while observing the reaction (unfortunately we do not have a “rate of reaction sensor”).

2. When choosing and listing apparatus

The plan must have:

• A detailed list of all lab equipment and materials used. Include quantities of each material

involved.

• A labeled diagram of the experiment setup can be referred to as part of the materials list.

• Measuring tools.

• Proper names for all equipment.

Sample Materials List

One clamp

One retort stand

One 20 cc syringe with cap

One 400 mL beaker

One hotplate

One thermometer

(-10 to 100°C ± 0.5)

ice

Note: Why is this list related to controlling variables?

When assessing the plan, consideration will be given to whether suitable apparatus are selected to make

measurements. For example, to measure 50 mL of solution, a beaker is unsuitable and uncontrolled means of

measuring volume.

3. When writing the procedure



• indicate where and how often data is collected (Aspect 3)

• are written to specifically address concerns about conducting a controlled experiment

• state the data processing and analysis requirements. For example “plot a suitable graph to

show the volume and temperature data” or “calculate the average time for each trial”.

A well-written procedure will ensure variables are properly controlled. Do not hesitate to include

extra information in a separate section at the end of the procedure that will help perform a good

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Student Guide


Criterion: DESIGN

experiment. For example “transfer quickly to avoid heat loss” or “allow at least one minute for the

apparatus to stabilize” are statements that will minimize error and help ensure the investigation is a

fair and scientific test.

Aspect 3 – Developing a method for the collection of data

This aspect evaluates the procedure, specifically whether enough data is collected.

In general

• Write the procedure in a concise and logical fashion.

• Write in numbered steps. Begin each step with a command verb. This is helpful when steps need to

be repeated for multiple trials so try to limit the instructions in each step to one task.

• The procedure must tell how and when to collect data. For example “measure the water

temperature at 60 s intervals, using the thermometer, until the liquid boils”.

Make sure sufficient data is collected. This means:

• Mention every required measurement.

• Plotting trends on a graph requires a minimum of 8 to 10 data points (good labs have

more). This implies that the independent variable must be manipulated at least that

many times and that the range of data collected is suitable and sufficiently large

• Repeated measurements (that are averaged) are often required. Usually a minimum of 3

trials is sufficient.

Hint: The DESIGN component evaluates your plan which is, in essence, a plan (you may not

do the investigation). DON’T skimp on the amount of data collected. PLAN to collect a

glorious amount of data.

A note about audience:

Write the procedure with the intention that average Grade 9 or 10 students could collect the materials

and perform the experiment with no other extra help. Proof read carefully, eliminate extraneous

instructions, and keep things simple.

Sample Procedure

1. Set up the equipment as illustrated in the diagram. Depress the syringe to a volume of

about 10 cc and cap before placing in beaker.

2. Add water and ice to the beaker. Insert thermometer and measure the lowest stable

temperature. Record air volume in syringe.

3. Turn on the hot plate and slowly heat the water.

4. Adjust the hot plate so the temperature stabilizes at about 20° C. Record air volume in

syringe.

5. Continue heating in 10° to 15° increments, allowing temperature to stabilize at each

increment and then record the air volume in the syringe. Stop heating when water is close

to boiling.

6. Plot a graph of absolute temperature and air volume data to determine the relationship

between the two variables.

Controlling Variables

• Ensure syringe is completely submerged in water bath

• Do not measure volume until temperature is stable for at least 60 seconds

• Place thermometer near syringe and halfway down in beaker

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Student Guide


Criterion: DESIGN

Summary of IB Evaluation Criterion: DESIGN


Aspect 2 –Controlling Variables

This aspect evaluates control of variables in the procedure you design.

• The method must include explicit reference to how the control of variables is achieved.

• If control is difficult, some effort should be made to monitor the variables.

Aspect 3 –Developing a method for collection of data

This aspect evaluates the procedure for the collection of sufficient relevant data.

• Ensure the procedure indicates when measurements are made.

• Repeating measurements is important especially in situations where measurement

techniques are not precise (using a stopwatch to measure the period of a pendulum).

• The range of values selected for the independent variable must be sufficient.

• There must be enough points within the selected range.

Other points

• In many scientific journals, procedures are written in the past tense and are basic summaries of

what was done. If you do an extended essay in Physics, Chemistry or Biology, you may choose to

use this style.

Sample Procedure (Summary Style)

A capped 20 cc syringe was used to contain a fixed mass of air. The syringe was immersed in a

number of water baths of varying temperatures from just above freezing to just below boiling. After

allowing time for the temperature of the bath and air in the syringe to stabilize, the water bath

temperature and air volume were measured. This data was then plotted on a graph.

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Revision 02: August, 2009

Student Guide


Criterion: DATA COLLECTION AND PROCESSING

This document is intended as a guideline for success in IB internal assessment. Three criteria are assessed

based on lab work submitted in a report or other format. They are: DESIGN, DATA COLLECTION AND

PROCESSING, and CONCLUSION AND EVALUATION. Each criterion is divided into three aspects which are

individually evaluated.

Data collection and processing (DCP)

The IBO rubric for DCP is shown below:

Aspect 1 – Recording raw data This aspect evaluates the presentation of observations and data collected during the course of the

experiment. Such data is called raw data and will consist of the measurements you made during the lab.

Raw data must be presented neatly and in a format that is easy to understand. This will almost always

require a table.

Data Table Reminders

• Use a standard row/column format

• Draw a box around the table and use lines where appropriate to separate rows/columns of

data

• It is common practice to write the independent variable data in a column to the left of the

dependent variable data.

• Table headings must include units of measurement and any applicable uncertainties

• Titles for tables are very important. Titles must be meaningful and contain a written

description of data presented.

• Do not overlap a table on two pages. Keep all data on one page!

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Student Guide



Example

Table 1: Change in volume of a fixed mass of air with increasing temperature.

Absolute Temperature

/ ±±±± 1 K

Volume of Air

/ ±±±± 0.3 cm3

274 10.2

301 11.2

316 11.8

342 12.7

369 13.7

Notes

• Units of measurement are critical. The slash “/” is used to denote units of measurement.

Alternative presentation uses parentheses.

• The title is descriptive and includes “Table 1”. Numbering tables makes discussion of data

easier because you can easily refer to a specific table.

• All measurements are made and recorded to the same precision (the same number of decimal

places) and the uncertainty is an absolute value (not a percentage) and given to one significant

figure.

• If uncertainty is negligible, ignored or requires other explanation, present justification as a

footnote under the table.

• Data included in tables can be quite cumbersome to present if there is a great deal of raw data or

if multiple measurements are made. Give this some thought and make the appropriate effort to

present the data clearly.

Qualitative observations are critical to fulfilling this criterion aspect. These observations can be

listed, presented as an annotated diagram, written as a short narrative or incorporated into the

raw data table. Examples of qualitative observations include:

• In chemistry labs involving reactions, observations should be made before, during

and after the reaction. Identify color changes, gas production, etc.

• Observations related to difficulties making measurements or anything that might

influence the data

Example

“It was noted that the syringe plunger jumped at times not sliding smoothly which may influence the volume

measurement”

Summary of IB Evaluation Criterion: Data Collection and Processing


Aspect 1 –Recording raw data

This aspect evaluates the recorded quantitative and qualitative observations made during the

experiment.

• Ensure relevant qualitative observations are included.

• All quantitative measurements must include units and a reasonable uncertainty.

• Pay attention to significant digits in both the data and uncertainties.

Aspects 2 and 3- Processing raw data and Presenting Raw data is processed in the analysis section and the results presented (Note: it is

quite common for both raw and processed data to be presented together). Data

processing includes any calculated values obtained from raw data and averages.

Processing also includes plotting raw data (and/or calculated values) on a suitable

graph, converting sketches to formal diagrams etc. Plotting raw data on a graph

without

• transforming to produce linear plot

• a line of best fit (and slope calculation)

• max/min lines

DOES NOT constitute processing!

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8.314510 8.3% error 100%

8.314510

% error 0.12%

−

= ×

=

The most important consideration when processing data is to perform calculations correctly. For

assessment purposes, it is essential that an example for each calculation is presented clearly to

show the method or rationale utilized.

Presenting processed data 1 - TABLES:

• it is essential to distinguish raw data from processed data in tables. If you wish to combine

data into one table, one way to indicate columns of processed data is to use a double line.

• sample calculations are presented after a table to clearly show how the processed table

values were obtained. YOU DO NOT NEED TO SHOW A CALCULATION FOR EACH LINE OF

DATA.

• uncertainties should be determined wherever possible (calculated or estimated) for ALL

processed data including best fit lines on graphs. Include an example that shows how the

uncertainty was calculated or determined.

• if an uncertainty is not significant – this must be mentioned and explained

Example

Table 2: The effect of increasing pressure on the volume of

a fixed quantity of hydrogen at a constant temperature (293 K).

Raw Data Processed Data

Pressure

/±±±± 0.1 kPa

Gas Volume

/ ±±±± 1 mL

R (gas constant)

/J••••mol-1••••K-1

101.3 456 8.32 ± 0.08

145.6 317 8.31 ± 0.08

198.2 233 8.32 ± 0.09

246.9 185 8.2 ± 0.1

302.0 152 8.3 ± 0.1

353.4 131 8.3 ± 0.1

Mean Value 8.3 ± 0.1

Sample calculation of R and uncertainty (∆R) using first row of data.

Note that volume data is converted to dm3, T = 293 ± 1K, n = 0.01894 ± 0.00005 mol

Calculate R Uncertainty in R

Uncertainty in mean Error in Experimental Mean Accepted value for R = 8.314510 J•mol-1•K-1 (Serway, 2002)

To determine percent error in experimental mean:

32.8

)293(01894.0

)456.0(3.101

=

=

=

R

R

nT

PVR

0.1 1 1 0.000058.32

101.3 456 293 0.01894

0.08 (one S.F.)

P V T nR R

P V T n

R

R

∆ ∆ ∆ ∆ ∆ = × + + =

∆ = × + + +

∆ = ±

max min

2

8.4 8.2

2

0.1 (one S.F.)

R

R

R

−∆ =

−∆ =

∆ = ±

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Note the following:

• the title describes the conditions of the experiment including the fixed conditions (quantity of gas

and temperature are controlled variables)

• a double line separates measured values from processed values

• a sample calculation for R is shown below the table (including uncertainty)

• the uncertainty for each calculated value of R varies so it is included directly in the table (instead

of in the heading)

• showing the calculation of mean with uncertainty is not usually required i.e. it is a standard

calculation regardless of the nature of the data

• the percent error in the mean (deviation from accepted value) calculation is performed here.

This comparison will be required in the Conclusions and Evaluation section of the lab report.

• the literature value is referenced

Presenting Processed Data 2 – Graphs: • only use graphing software if you know what you are doing. There is nothing wrong with a hand

plotted graph on proper paper.

• graphs should be at least one third of a page in size

• paste graphs into the body of the report so that a logical sequence of information is presented

Example (from Table 1 data)

Graph 1: The relationship of the volume of air in a syringe subjected to an increase in absolute temperature

This graph shows the linear relationship between the independent and dependent variables in this

investigation. If a trend is not linear, attempts must be made to manipulate variables mathematically

(transformed) to obtain a straight line relationship. The transformed graph would be presented after the

original graph and would probably be the main focus of discussion.

Notice how the x-axis uncertainty bars appear on the graph. If the uncertainty is very small relative to the

scale on the axis, the uncertainty bars can be too small to see. This should be noted on the graph (for

example, include in the title that due to the relatively small uncertainty, the uncertainty bars for

Temperature are too small to be included).

Maximum and minimum best fit lines are included to determine the uncertainty in the slope of the

plotted best fit line. This is essential!

274 10.2 10.5 9.9

301 11.2

316 11.8

342 12.7

369 13.7 13.4 14

y = 0.0368x + 0.1424

9

10

11

12

13

14

250 300 350 400

Temperature / K

Vo

lum

e / c

c

Slope = 0.037 ± 0.06 cc K-1

Temperature / ± 0.1 K

Vo

lum

e /

±1

cc

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Don’t forget: Your graph must include

• descriptive title

• labeled axis with units

• appropriate scale

• properly plotted points with uncertainty bars (or an explanation if not included)

• line of best fit (linear or curve)

• the equation of line – if linear (use points on the best fit line to calculate)

• legend or key (if more than one series of data)

Students often fail to realize the significance of data processing and tend to focus more on presenting

processed data. The analysis of data has three primary purposes:

1. Determining if there is a linear trend relating the two plotted variables and expressing the trend

mathematically (i.e. y = mx + b or y = kx2 etc.). This requires graph analysis.

2. Comparing a calculated value to a known or accepted value. This may mean comparing a slope,

extrapolated or average value to a quantity obtained from the literature (for example comparing

an experimental value of “g” to 9.81 ms-2) or an expected result (for example the slope of a graph

might be expected to be a certain value).

3. Looking at data values (plotted or otherwise) for evidence of random or systematic error.

For data analysis to mean something, you must understand what you are looking for.

Summary of IB Evaluation Criterion: Data Collection and Processing


Aspect 2 –Processing raw data

This aspect evaluates the manipulation of raw data values.

• Double check calculations are correct.

• A trend line must be included for any plotted data.

Aspect 3 –Presenting processed data

This aspect evaluates the presentation of processed data including the propagation of uncertainty, and

utilizing a suitable presentation format that effectively communicates the processing.

• Include a sample calculation for each manipulation performed. Present clearly so the reader

can understand where substituted values come from and the nature of the calculation.

• All graphs and tables need to have clear, unambiguous headings.

• All graphs require axis labels, units, and appropriately plotted points, uncertainty bars and

trend lines

• Choose a suitable scale for any graphs.

• Uncertainties must be propagated in any calculations. Uncertainties on graphs usually

require the drawing of appropriate max/min best fit lines.

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Criterion: CONCLUSION and EVALUATION

This document is intended as a guideline for success in IB science internal assessment. Three criteria are


AND PROCESSING, and CONCLUSION AND EVALUATION. Each criterion is divided into three aspects which

are individually evaluated.

Conclusion and Evaluation (CE)

The IBO rubric for CE is shown below:

Aspect 1 – Concluding Meeting this criterion aspect requires a statement of results with an explanation and conclusions. The

conclusion should be supported by the data and a statement of validity for the experimental result. This

may mean doing some research in order to compare an experimentally determined value with an

accepted value from the literature.

The conclusion paragraph(s) can be simply broken into four parts:

• A knowledge claim

• Evidence and/or discussion to support the knowledge claim

• Relating the result to physics principles and a comparison to a known value if possible.

• An indication of the presence of any experimental error (random or systematic)

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TP

nRV =

For example (refer to data in previous section)

“The investigation indicates that there is a linear relationship between volume and absolute

temperature”. - this is the knowledge claim

“This relationship is indicated by the best fit line in Graph 1. Mathematically V ∝ T which supports the

relationship described by Charles’ Law:

The value of “nR/P” is constant and is equal to the slope of the line. From the slope, a value for R in this

investigation was determined to be 8.30 ± 0.06 J•mol-1•K-1. This compares favorably with the value of

8.31 (rounded) found in the reference section of Serway and Faughn, 2002. The percent error is 0.12%

which is less than the relative uncertainty 0.7% associated with calculated result therefore it can be

concluded that the experimental value agrees with the literature value within the measurement

limitations of the procedure.” - evidence to support claim and comparison to literature value

The data plotted is very consistent with the trend line and shows little evidence of random error. The

equation of the line indicates a small y-intercept value of 0.1424 which may indicate a systematic error

or might also be a result of experiment uncertainty. As the origin is contained by the maximum and

minimum best-fit lines it can be concluded that within the range of experiment uncertainty, volume is

proportional to absolute temperature.” - indication of the presence of error

Summary of IB Evaluation Criterion: Conclusion and Evaluation


Aspect 1 –Concluding.

This aspect evaluates the validity and support of a conclusion statement.

• State the conclusion clearly and early.

• Make sure the conclusion is based on a reasonable interpretation of the data.

• A percent error calculation is made when comparison to a known value is possible. This

error should be compared to the experimental uncertainty and thereby indicate confidence

(or lack of) in the obtained result. Comment on the presence (or absence) of random or

systematic errors in the data.

Aspect 2 – Evaluating procedures Evaluation of the lab is one of the more difficult sections. Students must critically examine the entire lab


analyzed in an attempt to identify and evaluate the significant limitations or weaknesses. Furthermore,

you are expected to provide realistic suggestions to improve where fault has been identified.

Limitations or weaknesses can address:

• measuring equipment of low precision (> 5% relative uncertainty)

• invalid assumptions

• indirect measurements

• not enough measurements

• difficulty making accurate measurements

• calculated values with high uncertainties (> 5%)

• variables that are difficult to control such as friction, air resistance and heat loss

• systematic errors built into the lab

• improperly calibrated lab equipment

• poor management of time (in a self-designed procedure)

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Human mistakes are not considered to fall in this category. If you made a mistake during the lab, it is not

acceptable to publish incorrect results and then blame it on a mistake you knowingly made. Care must be

taken to ensure this does not occur and may mean you arrange an alternate time to repeat a lab that has

been ruined by careless technique.

Students often fail to meet this aspect fully because they ONLY IDENTIFY weaknesses or limitations

and present only a list of problems without any supporting information. To satisfy the criteria the

effect of the identified weakness or limitation must be DISCUSSED AND EVALUATED.

Use the following template to help you write this last section:

1. What are the weaknesses or limitations in the lab activity procedure?

2. How did this weakness or limitation affect the precision or accuracy of the result? Support your

argument by referring to the data.

3. What specific and realistic improvements to address the fault (this is aspect 3).

It is useful to brainstorm in chart format:

Weakness or Limitation Evidence in Data

Effect on accuracy or precision

Possible modification to

minimize or eliminate this

weakness

Aspect 3 – Improving the investigation

There are two important things to remember in this section:

• Suggest an improvement for each weakness or limitation identified in the evaluation.

• Improvements must be specific, and realistic. Suggestions to use a “more accurate ruler” are not

acceptable. If there are no realistic suggestions, make note of that.

BE CAREFUL WHEN EVALUATING FAULTS IN AN EXPERIMENT to focus on those that have a significant

effect on the results. A sufficient lab discussion addresses 2 or 3 of the most significant limitations,

weaknesses or errors and provides in depth reasoning. Do not focus on small things and miss the big

picture. Think critically! Here is an analogy:

“Bob always writes his tests with a red pencil.

The night before the test, Bob skips most of

his regular study time to play basketball. The

next day, Bob shows up and writes the test

but has forgotten his red pencil. Instead he

uses a blue pencil. Bob fails the test and

blames it on the color of his pencil”

It is clear that Bob failed because he didn’t

study, not because his pencil was a different

color. The color may have had a small

psychological effect but it would be minimal

compared to doing less studying. Relate this

to any experiment, and when writing focus on

the big (not studying) limitations not the

small (color of pencil) ones.

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When writing the evaluation section it is suggested that each new limitation or weakness discussed is

listed in a separate paragraph. Ensure you clearly explain the weakness, how it may have affected the

data and its impact on the result. Finish the paragraph by suggesting (with explanation) a realistic

improvement.

Examples

“The y-intercept of Graph 1 indicates a systematic error in the volume measurement possibly due to the cap

placed on the end of the syringe. It is likely that the measured volume using the graduations on the side of

the syringe is incorrect. The systematic error could be explained as the actual volume (including the cap)

being more than measured volume. This error could be eliminated by calibrating the capped syringe by

drawing a known volume of distilled water and then comparing with the syringe scale reading”

Look for measurements (or calculated values) that have high (> 5%) relative uncertainties:

“The uncertainty in the volume measurement is quite high compared to the actual measured volume (about

3% relative error for the 10.2 cc measurement). The data indicates that the change in volume for the entire

temperature range was 3.5 cc (13.7 – 10.2). As this range is quite small compared to the 20 cc capacity of

the syringe, the precision of the volume measurement could be improved by using a smaller 5 cc syringe with

small volume scale graduations. This would yield data with smaller relative uncertainty values.”

Other explanations for possible systematic and/or random errors:

“A limitation of this experiment is the temperature measurement. Temperature of the water bath is

measured and it is assumed that enough time is allowed for the apparatus to stabilize so that the gas

temperature in the syringe matches the temperature of the water. It is likely that the temperature in the

syringe lags behind that of the temperature in the water bath (actual gas temperature is less than recorded).

A better solution would be to use a specially constructed syringe containing a temperature probe that

directly measures the inside gas temperature”

“The plunger of the syringe was observed to not slide smoothly at times during the heating process. This is a

possible source of random errors in volume measurements. Again, a water bath that allows the apparatus to

stabilize at a constant temperature would help here.”

“Charles’ Law is specifically stated for an ideal gas. Air is not an ideal gas and it is unlikely that it is pure.

One possible impurity would be water. Moisture in the air might adversely affect the accuracy of the volume

measurements over the given temperature range. The experiment would be better conducted using a pure

sample of a bottled gas such as helium”

Summary of IB Evaluation Criterion: Conclusion and Evaluation


Aspect 2 –Evaluating procedure(s)

This aspect evaluates the identification of weaknesses and limitations

• Ensure the identified weaknesses/limitations are relevant and supported by the data.

• Explain why the identified weakness/limitation adversely affected the result of the

experiment.

Aspect 3 – Improving the investigation

This aspect evaluates suggested improvements to address identified weaknesses/limitations.

• Ensure the suggestions are realistic.

This document is intended as a guideline for success in IB ...pedagogics.ca/files/IBWritingGuide/pedagogics/IB IA Guide - Full... · This document is intended as a guideline for success

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