The Working of Scientists

Leela Raj

Jonathan Levin High School for Media and Communications, Bronx

Summer Research Program for Science Teachers

August 2009

Grade Level: 9th and 10th

Unit: Scientific Method

Aim: How can you design a science experiment?

Objectives:

Students will be able to, to a 90% accuracy, by discussion, observation and hands-on activity,

·        Devise ways of making observations to test proposed explanations

·        Develop and present proposals including formal hypothesis to test their explanations

·        Define and explain the basic concepts of experimental design (control, variables)

·        Carry out their plan for testing explanations, including selecting and developing techniques and recording observations as necessary

·        Organize their findings and make a presentation

Vocabulary:

• hypothesis
• dependent variable
• control group
• data
• results
• independent variable
• repeated trials
• experimental group

Materials/Preparations: Per Group:

1.    Triple beam balance graph papers

2.     A crumpled paper ball

3.     A plain paper

4.     A rubber ball

5.     A paper clip

6.     A thick book

7.     A thin book

8.     Stop watch

9.     Graph papers

10.   Chart papers

11.   Color pencils

12.   Scientific Method Worksheet

Do Now:

Give examples to students such as:

‘A researcher wants to know if Lower-BP, a drug for lowering blood pressure works effectively on humans’.

Ask  the students to identify the 5 different steps  of the scientific method

Developments/Instructional Strategies:

Mini Lesson:

Designing an experiment to build science skills.  Discuss the dependent and independent variables in an experiment.

Use concept map and draw on the board

1.   Ask a question

2.   Form a hypothesis

3.   Set up a controlled experiment

4.   Record and analyze

Group Activity:

The following activity has been designed to provide the basis for

observation, data collection, reflection and analysis of the events.

Show to the class  the different objects listed above.  Ask:

If these objects are let to free fall, which object would touch the ground first?

Ask them to write their hypothesis and share it with others.

Divide class into small groups. After they have shared their hypotheses, ask them to come up with questions that they would like to explore about this activity and how to investigate the question. Challenge students to come up with as many questions as possible and ask them to share what they are going to explore and how they might conduct their proposed exploration. Lead the class to an open discussion and have them agree on one question that the whole class can work on. Remind students about materials available for this investigation.

To help students in this process, ask them to do the following:

1.   Weigh the objects one by one and record their weight.

2.   Gently push them from the edge of the table to give them a ‘free fall’

3.   As you start pushing them, record the time in the stop watch.

4.   Conduct 2 trials and calculate the average.

5.   Represent your data in tables and in bar graph.

6.   Vary the dependent variables (height, weight) (time permitting)

Independent Activity:

Give some research problems to the students and ask them to complete the worksheet.

Some examples:

1.    How can you test whether plants require sunlight?

2.    Does meat get rotten if left outside?

3.    How can you test the effect of  a growth supplement X on people?

4.    Is paper towel A more absorbent than paper towel B?

Summary: Finish the lesson by having each group give a presentation to the class about how they would test their hypothesis, how they would collect the data, and how they would represent the data.

Suggested Homework:

(From a past Living Environment Regents Exam)

Many plants can affect the growth of other plants near them. This can occur when one plant produces a chemical that affects another plant. 

Design an experiment to determine if a solution containing ground-up goldenrod plants has an effect on the growth of radish seedlings. In your experimental design be sure to:

• State a hypothesis to be tested

• Describe how the experimental group will be treated differently from the control group

• Explain why the number of seedlings used for the experiment should be large

• Identify the type of data that will be collected

• Describe experimental results that would support your hypothesis

Standards:

New York City Standards: Key Idea 2

Performance Indicator 2.4

Carry out a research plan for testing explanations, including selecting and developing techniques, acquiring and building apparatus, and recording observations as necessary