Beacon Lesson Plan Library

Whodunit?

Helen Fling

Description

The purpose of this lesson is to practice using the scientific method with a theoretical problem and provide students with the information management skills necessary to understand and creatively analyze the cause and effect(s) of an event.

Objectives

The student knows that scientists can bring information, insights, and analytical skills to matters of public concern and help people understand the possible causes and effects of events.

Materials

- Masking tape
- Closable plastic bags, or small film canisters (1 per group)
- Different unknown samples such as baking soda, baking powder, corn startch, cream of tarter, salt, sugar, alum, et cetera (1 per group)
- Clear plastic cups (8 ounce), or 50 to 100 milliliter beakers (1 per group)
- Candles, or Bunsen burners (1 per group)
- pH indicator (litmus paper, or red cabbage juice, to name a few possibilities)
- Spoons
- Triple beam balance

Preparations

1. Review the importance of safety and sterile sample collection techniques.
2. Reintroduce the scientific method and its importance in matters of public concern.
3. These should be covered prior to this lesson: pH, solubility, melting point, and crystallization.

Procedures

BEFORE CLASS - Day 1
1. Create an outline of the murder victim on the floor with masking tape.

2. Tactfully place trace evidence, Choose one of the unknown samples such as baking soda, baking powder, corn startch, cream of tarter, salt, sugar, alum, et cetera (to be collected by the students).

DURING CLASS - Day 1
3. Role play, for example: What’s going on here? Did anyone see what happened? We’ve got to figure out what went on here! It must have been a poisoning because there are no signs of a struggle. No one knows who did this? How can we find out?

4. Distribute the Student Data Sheet that is in the associated file. Allow students to complete the sections titled Observations, Hypothesis, and Procedures. Direct students to develop a plan-of-attack that must include collecting evidence, testing evidence, and recording data at the very least.

5. Introduce the four criteria that will be tested: solubility, melting, pH, and crystallization (optional - growing crystals will take about one week).

6. Divide students into groups to run tests on the trace evidence which was collected by the students such as baking soda, baking powder, corn startch, cream of tarter, salt, sugar, alum, et cetera; and record data in the table on the Student Data Sheet. Make sure to clearly state: We know one of the groups in this class must have committed the murder. By using scientific investigation to determine which group has a substance that matches the trace evidence, we can conclude WHODUNIT!

DAY 2
7. Compare and correct, as necessary, the class data for the sample found at the murder scene obtained yesterday to ensure everyone has the correct information to use for comparison.

8. Distribute a different unknown sample such as baking soda, baking powder, corn startch, cream of tarter, salt, sugar, alum, et cetera to each group. Explain that only 1 group in the class has the same substance as the evidence found at the scene of the murder.

9. Allow groups to test their own samples and record data in the table on the Student Data Sheet.

10. Clean up!

11. Compile class data from each group. Have students use this data to compare/contrast each group’s sample to the sample found at the murder scene and conclude WHODUNIT? One group per class will have a sample whose data matches all of the data for the trace evidence, which was originally collected by the students. This group will be the only group that can be linked to the murder scene.

DAY 3
12. Discussion/Review

13. Extensions/Assign follow-up classwork/homework

Assessments

This activity provides each student with practice bringing information, insights, and analytical skills to matters of public concern and relating this information, insights, and skills to the possible causes and effects of such an event.

Each student should be assessed on the following:
- Records the observations of the mock crime scene,
- Writes a hypothesis/restates the problem about the cause of the mock murder in a complete sentence,
- Accurately compiles data from other groups in the class into the table provided on the Student Data Sheet,
- Uses inductive tools to solve the mystery (analyzes the data in the table to give an insight as to WHODUNIT?) and
- Draws/writes a conclusion/summary in complete sentences that is based on the data in the table, and that expresses the importance of science to matters of public concern (e.g. crime scenes).

* Circulate through the classroom to observe management of information and guide any students who may have questions, and to make sure they are not taste testing any sample. (Note progress on particular problem areas.)

Extensions

As a follow up/homework try one of the mysteries on crimescene.com.

Web Links

Web supplement for Whodunit?
Crime Scene

Attached Files

Student Data Sheet     File Extension: pdf

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