Introduction to laboratory techniques

Unit 1: Introduction to Laboratory Techniques

1.5 Data Tables and Graphs

Data tables and graphs

• Why are tables and graphs important is science?

Data tables and graphs

• Making data tables and graphs are useful tools for both recording and

communicating scientific data.

Data tables and graphs

Making data tables

• You can use a data table to organize and record the measurements that you make .

• Some examples of information that might be recorded in data tables are frequencies, times, and amounts.

Making data tables

• Example:– Suppose you are investigating photosynthesis in

two elodea plants. One sits in direct sunlight, and the other sits in a dimly lit room. You measure the rate of photosynthesis by counting the number of bubbles in the jar every ten minutes.

– How would you make a table to organize and record the data you collect?

Making data tables

• 1. Title and number you data.• 2. Decide how you will organize the table into

columns and rows.• 3. Any units, such as seconds or degrees,

should de included in column headings, not in the individual cells.

Making data tables

• Table 1. Number of Bubbles form Elodea

Time (min) Sunlight Dim light

0 0 0

10 15 5

20 25 8

30 32 7

40 41 10

50 47 9

60 42 9

Making data tables

• The data in the table could also be organized in a different way.

• How?

Making data tables

• Table 1. Number of Bubbles form Elodea

Light condition

Time (min)

0 10 20 30 40 50 60

Sunlight 0 15 25 32 41 47 42

Dim light 0 5 8 7 10 9 9

Put units in column

heading.

Home work• Observing the parts of flowers– Process Skills:• Observing• Collecting and interpreting data• Inferring

– Materials:• Plastic knife• Newspaper• Hand lens• 2 different flowers

Home work

– Procedure:• 1. Collect two different types of flowers from your

garden or neighborhood.• 2. Spread newspapers on the floor.• 3. Collect the following data: number of sepals, color of

sepals, number of petals, color of petals, number of stamens, number of pistils, drawing of stamen, drawing of pistil.• 4. Record the information collected on a table.• 5. Answer the following questions:

Home work

• Explain how the parts of the two flower s are similar and different.• What might you infer about the parts of other flowers

with four parts? How might they be similar to these flower parts? How might they be different?

*Present your homework in the form of a lab report. The questions and answers should be included as your conclusion. In this report you do not need to include a hypothesis nor an introduction.

Home work

Bar Graph

• A bar graph is a type of graph in which the lengths of the bars are used to represent and compare data.

• A numerical scale is used to determine the length of the bars.

Bar Graph

• Example:– To determine the effect of water on seed

sprouting, three cups were filled with sand, and ten seeds were planted in each. Different amounts of water were added to each cup over a three-day period.

Bar Graph

• Table 1. Effect of Water on Seed Sprouting

Daily amount of water (mL)

Number of seeds that sprouted after 3 days in sand

0 110 420 8

Bar Graph

1. Choose a numerical scale. The greatest value is 8, so the end of the scale should have a value greater that 8, such as 10.

2. Draw and label the axes. Mark intervals on the vertical axis according to the scale you chose.

3. Draw a bar for each data value. Use the scale to decide how long to make each bar.

0

1

2

3

4

5

6

7

8

9

0 10 20

Num

ber o

f spr

outin

g se

eds

Figure 1. Effect of Water on Seed SproutingBe sure to add a number

and a title

Label each bar

Label the

scale

Water added each day (mL)

Double Bar Graph

• A double bar graph is a bar graph that shows two sets of data.

• The two bars for each measurement are drawn next to each other.

Double Bar Graph

• Example:– The seed-sprouting experiment was done using

both sand and potting soil. The data for sand and potting soil can be plotted on one graph.

1. Draw one set of bars, using the data for sand, as shown below.

2. Draw bars for the potting-soil data next to the bars for the sand data. Shade them a different color. Add a key.

Double Bar Graph

• Table 2. Effect of Water and Soil on Seed Sprouting

Daily amount of water (mL)

Number of seeds that sprouted after 3 days in sand

Number of seeds that sprouted after 3 days in potting soil

1 1 2

10 4 5

20 8 9

0 10 200

1

2

3

4

5

6

7

8

9

10

SandPotting Soil

Figure2. Effect of Water and Soil on Seed Sprouting

Num

ber o

f spr

outin

g se

eds

Water added each day (mL)

Make key to show what each color represents

Leave room for “potting –soil” bars.

Class work

• Practice collecting and interpreting data.– Materials: • Pencil• Ruler• Paper

Class work

• Procedure:– Make a chart to record how many of your

classmates have blue eyes, brown eyes, black eyes or green eyes.

– Make a chart to record how many of your classmates have blonde hair, red hair brown hair or black hair.

– Make a chart to record how many of your classmates are 14, 15 or 16 years old.

Class work

– Take a survey to collect the data on hair color, eye color and age. Make a tally mark for each student’s answer in the correct place on the charts. Then calculate the total number of students for each answer.

– Draw three bar graphs or a triple bar graph to show your results. Make sure to label the X and Y axes. Use different colors to make a key to distinguish each bar.