Grade 3 Topic II Working Like a Scientist Lesson B The Role of Theories, Laws, Hypothesis, and Models Office of Academics - Department of Science.

Grade 3 Topic II Working Like a Scientist

Lesson B

The Role of Theories, Laws, Hypothesis, and Models

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GRADE 3 TOPIC II Benchmarks• SC.3.N.3.2 Recognize that scientists use models to help understand and explain how things

work. Cognitive Complexity: Level 1: Recall• SC.3.N.3.3 Recognize that all models are approximations of natural phenomena; as such, they

do not perfectly account for all observations. Cognitive Complexity: Level 2: Basic Application of Skills & Concepts

• LAFS.3.W.3.8 Recall information from experiences or gather information from print and digital sources; take brief notes on sources and sort evidence into provided categories.

• LAFS.3.SL.1.1 Engage effectively in a range of collaborative discussions (one-on-one, in groups, and teacher-led) with diverse partners on grade 3 topics and texts, building on others’ ideas and expressing their own clearly.

• MAFS.3.MD.1.2 Measure and estimate liquid volumes and masses of objects using standard units of grams (g), kilograms (kg), and liters (l). (Excludes compound units such as cm^3 and finding the geometric volume of a container.) Note: Add, subtract, multiply, or divide to solve one-step word problems involving masses or volumes that are given in the same units, e.g., by using drawings (such as a beaker with a measurement scale) to represent the problem. (Excludes multiplicative comparison problems (problems involving notions of “times as much.”)

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Using a model helps understand and explain how things work.

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Models are concrete examples that represent objects on a smaller scale, or ideas or events.

Models can be• three dimensional• two dimensional• computer models• diagrams

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LET’S MAKE A MODEL!

Use a model to represent a bridge and then develop an experiment that is testable and repeatable.

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Doing a Scientific Investigation

Scientific Investigation in Everyday Life (Click on image below to play video.)

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Doing a Scientific InvestigationAsk a question(Problem Statement)• Does the shape of a paper

bridge (the way the paper is folded) affect its strength to hold the most pennies?

Make an educated guess(Hypothesis)• Explain your reasoning. • Discuss if different kinds of

paper were used would this affect the stability of the bridge.

Develop a plan to carry out experiment (procedure or experimental setup)

Working in groups of 4, design two different bridges to determine which design will hold more pennies (more mass).

Use your science notebooks/journals to record all investigation information, including illustrations of the designs.

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Identify Variables

• Identify the test variable or independent/manipulated variable (one thing that changes in the experiment).

• Identify which is the outcome variable or dependent/responding variable (data to be collected).

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What You’ll Need:

Materials:• Three foam 8 oz. paper cups• Several sheets of 8X11 copy paper• Several pennies• Triple beam balance or balance with gram

mass pieces• Ruler

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Let’s Explore!Procedures to Follow:

1. Place the cups on a solid surface, such as a floor or table.

2. Place the cups 15 cm apart.

3. Create a paper bridge using one of the sheets of paper.

4. Fold the bridge any way you like.

5. Place the folded bridge design #1 between the paper cups so that it spans the length of the bridge evenly.

6. Place your pennies one by one in the center of the bridge on your roadway.

7. Count the number of pennies your bridge was able to support then find the mass (in grams) using a triple beam balance or balance and gram cubes. Record your data.

8. Repeat steps 1-7 with design #2 (new folded bridge).

9. Conduct two more trials for each design.

10. Record and report your findings.Office of Academics - Department of Science

DATA

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Number and Mass in Grams of Pennies

Trial 1 Trial 2 Trial 3 AverageNumber

of Pennies

Mass Number of

Pennies

Mass Number of

Pennies

Mass Number of

Pennies

Mass

Bridge 1

Bridge 2

Analyze and Interpret the Data: Draw a Conclusion

• Compare the number of pennies each bridge design was able to support before they collapsed.

• Did the data support your hypothesis? • If one held more than the other, why do think that

happened?

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All Student Groups Communicate and Explain Results

• Report on what the group did (experimental design) for their bridge investigation.

• Share their conclusion showing what evidence (data collected) they have to support or not support their hypothesis for the strongest bridge.

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Ask a New Question

• Students go back to their groups to review and refine their inquiry and can consider the following:

• Did they do at least three trials?• Should they revise their procedures and repeat their

investigation?• What new question(s) could be investigated?

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Brain CheckWhy do Scientists use models?

Scientists use models to help understand and explain how things work.

What are models? Models are concrete

examples that represent objects on a smaller scale, or ideas or events.

What are the steps to the Scientific Method?In a scientific investigation, scientists… Ask questions Make an educated guess

(Hypothesis) Develop a plan to carry out an

investigation Identify variables Collect and record data Analyze and interpret data Draw a conclusion Communicate and explain results Ask new questions

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