## Designing Detectives

### Lisa Ove GibsonBay District Schools

#### Description

Students explore the idea of formulating a hypothesis and designing an experiment to test the hypothesis. This is an introduction to the Unit Plan: Statistical Sleuths.

#### Objectives

The student formulates hypotheses, designs experiments, collects and interprets data, and evaluates hypotheses by making inferences and drawing conclusions based on statistics (range, mean, median, and mode) and tables, graphs, and charts.

The student formulates a hypothesis and designs an experiment.

The student evaluates the hypothesis by making inferences and drawing conclusions based on statistical results.

#### Materials

-Quickie Experiments (see page 1 of Associated File)
-Experimental Design Rubric (see page 2 of Associated File)
-T-Chart for Class Discussion (see page 3 of Associated File)
-Data Detective Diary (used throughout the Unit Plan: Statistical Sleuths)
-Classroom display board (examples: overhead projector or chart paper or chalkboard)
-Blank transparency film for copy machines or printers
-Corresponding writing device
-A tennis ball canister (cylindrical) or a soda can
-A piece of yarn or some other flexible measuring device that is longer than the length of tennis ball canister
-Specific materials referenced in the Quickie Experiments (water dropper, yardstick, food-colored water, white paper, ramp or inclined plane, tape measure, matchbox car, plastic ruler with grooves, round marble, stopwatch)
-Materials for the optional activity, #4 Melt Ice Cube in Quickie Experiments (a gardening glove (not rubber), at least two ice cubes of equal size)

#### Preparations

1. Review the terminology in Vocabulary for Statistical Sleuths which denotes terms that will be used throughout the unit. (See Unit Plan Associated File. Further information is available in Extensions.)

2. Prepare a large writing space in the front of the classroom to record the following items:
(a) Elements of a hypothesis (found in #3 of the Procedures),
(b) Elements of experimental design (found in #11 of the Procedures),
(c) Detective Diary entries (#2, #3), and (d) Comments/ideas generated during today's discussion.

3. Review Quickie Experiments (see page 1 of Associated File) prior to completing the Procedures for this lesson and secure all of the materials for the experiments that you plan to demonstrate for students.

4. Construct, provide, or require students to obtain a notebook with paper to be used as the Detective Diary for the Unit Plan. (Examples include spiral, three-prong, hand-made, etc.) Write the prompt on the chalk/white board for diary entry #3.

5. Prepare and disseminate the class procedures for cooperative work for your classroom. These rules for engagement are necessary if you decide to complete #15 of the Procedures and ask students to peer-assess the Detective Diary entries.

6. Prepare mini-lesson on how to formulate a hypothesis (see Procedures #3).

7. Select possible homework assignments that would reinforce concepts from this lesson. (Use appropriate pages out of your classroom text or some other resource for ideas.)

8. If using the Unit Plan: Statistical Sleuths, you might want to collect and secure each student’s Detective Diary after each lesson plan. The completed Detective Diary will be returned to students prior to the summative assessments for the unit and used for the information for review.

9. Review Compiled List of Detective Diaries for the entire Unit Plan: Statistical Sleuths to appreciate the purpose and scope and sequence of the diary during the formative assessments throughout the unit. (See Unit Plan Associated File. Further information is available in Extensions.)

#### Procedures

1. Special Note: Explain the purpose of the unit and the Data Detective Diary to students described in the Compiled List of Detective Diaries for the Unit Plan: Statistical Sleuths. (See Unit Plan Associated File. More information is available in Extensions.)

2. Show students a canister (cylindrical) in which tennis balls are sold, usually containing three balls per canister.

-Ask students: Which is longer, the circumference or the length?
-Also, how do we determine which is longer, the circumference of the tennis ball canister or the length of the canister?

For this example, students will not formulate a hypothesis exactly as it is outlined in #3 of these Procedures. This illustration is intended to offer the student an abbreviated version of how to formulate a hypothesis. Instead, the focus of this demonstration is to allow students to practice asking how and why questions, decide how to determine the answer to the question about which is longer, and practice predicting the outcome of event.

3. Discuss with students the elements of a hypothesis and record these ideas somewhere all students can see. Use the following notes, A-E, and ask students to record this information in their Detective Diary for future reference. These procedures should be used during all experiments conducted in today’s lesson.
(A) First observe an occurrence (event) and explore why it happens. Next, write down what happened in your own words.
(B) To further explore what happened, decide what you want to find out about the occurrence.
(C) Using your own observations and by designing how and why questions, write a statement that describes what you want to do. (This defines the purpose of the experiment.)
(D) Based on the how and why questions identified in the preliminary investigation, make a list of answers to each question.
(E) These answers should be worded in statements that describe the how or why of what happened in the occurrence. These statements become the hypotheses. One occurrence can have many hypotheses. Important note: A hypothesis must be stated in a way that can be tested by an experiment. By stating each hypothesis in this way, students can easily see the connection between the hypothesis and experimental design.

4. Conduct a class survey of answers to these questions: Which is longer, the circumference or the length? Also, how do we determine which is longer, the circumference of the tennis ball canister or the length of the canister? Ask each student for a response to these questions.

5. Use the T-Chart for Class Discussion to separate student responses. (See page 2 of the Associated File.) Display T-Chart for Class Discussion on the chalkboard, chart paper, or overhead projector.

6. Conduct the actual experiment involving the tennis ball canister. This should be completed after students understand how to formulate a hypothesis and how to design an experiment to test the hypothesis. Show them a piece of yarn. (Make sure that the yarn is longer than the length of the canister or use some other flexible measuring device.) First, measure the length of the canister. (Most students will answer that the length of the canister is longer than the circumference.) Keep your fingers in the positions denoting the ends of the canister. Then, wrap the yarn around the middle of the canister, making sure to keep your fingers where you marked for the length. The circumference of the canister is longer than the length. Model questioning techniques to discover why this outcome occurred. (Extension: See Weblinks section of this document for discovery lessons that can be used to extend student understanding of this math/visual phenomena.)

Part II:
7. Provide a copy of Experimental Design Rubric for each student and explain that it will serve as guidelines for today's diary entries. (See page 3 of the Associated File.) Answer any student questions regarding the rubric.

8. Present only the problem (#1- Splatter Size, #2- Rolling Cans, #3- Roll Marble Down Ruler) to students from the activity sheet Quickie Experiments. (See page 1 of the Associated File.) Do not present the Procedure for Solution until after students have formulated a hypothesis in Detective Diary #2 about the probable outcome of each experiment. Experiment #4- Melt Ice Cube is an optional activity.

9. Write this entry in an area that all students can see, Detective Diary Entry #2 for students: Formulate a hypothesis about what you think will happen in each of the Quickie Experiments #1 – 3. (See page 1 of the Associated File.) Ask students to write these hypotheses in their diaries. The purpose for these activities is to illustrate the concepts of prediction and formulating a hypothesis for students. Because these experiments have already been designed, the role of the student will be to identify the original hypothesis and to try and describe how and why a particular outcome is possible in each experiment. (Additional experiments may be necessary for your students to feel comfortable with this concept. For more experiments, see the Weblinks section of this document.) This entry follows the diagnostic assessment Entry #1 that is described in the Unit Plan: Statistical Sleuths. Detective Diary #2 serves as the formative assessment.

10. After every student has completed Detective Diary #2 (formulating each hypothesis #1 - 3 and describing how and why a particular outcome is possible in each experiment), then physically conduct each Quickie Experiment for class demonstration. (See page 1 of the Associated File.) Special note: Before demonstrating these experiments, explain to students that they will record observations, questions, and ideas in the Detective Diary.

11. Discuss ways to find out how we can determine if our hypotheses are true. This leads to a discussion of the elements of experimental design. Use the following notes, A-D, and ask students to record this information in their Detective Diary for future reference. Record these ideas somewhere so that all students can see. Experimental design begins by identifying a step-by-step list of what you will do to answer the statements of how or why called hypotheses. This list of what you will do is known as the procedures. Here are some guidelines for this process:
(A) Select only one thing to change (also known as the variable) in each experiment conducted,
(B) Make sure that the single thing that you decide to change will help you test the hypothesis,
(C) Make sure you explain how you will change the one thing and also explain how you will measure the change, and
(D) Finally, decide what materials and equipment you will need to collect the data that you need to verify the original hypothesis. The design of the experiment that the student plans to use to test the hypothesis should be reasonable (affordable, appropriate for an eighth grader to accomplish), clearly explained, and possible within the constraints of the scientific process.

12. Provide formative feedback by conferring with students in an individual conference or through a whole class discussion. Make sure they comprehend the concepts of formulating a hypothesis and designing an experiment.

13. Follow-up for Detective Diary #2: After seeing the results of the experiment, evaluate your hypothesis from Detective Diary #2 for each experiment by making inferences and drawing conclusions based on observations from the demonstration. Were your assumptions on target? Did you consider all of the variables in your hypothesis that shaped the outcome during the demonstration? Follow-up for Detective Diary #2 serves as the formative assessment.

14. Pose the class question: How much time should the average eighth grade student spend on homework per week to make good grades (a B average or higher)? Write this entry in an area that all students can see for Detective Diary Entry #3: Students formulate a hypothesis and design an experiment to test how much time the average eighth grade student should spend on homework per week to make good grades. Detective Diary #3 serves as the formative assessment.

15. As a class, students self-assess and peer-assess diary entries #2 and #3 using the criteria listed on the Long-Answer Question Rubric. (See Unit Plan Associated File. Further information is provided in Extensions.) Note: This activity is designed to help students understand how the teacher will evaluate the completeness of their response.

16. Collect Detective Diaries and check student responses using the Long-Answer Question Rubric. (See Unit Plan Associated File. Further information is available in Extensions.) Formatively assess students' responses to the diary entry. If using the Unit Plan: Statistical Sleuths, then return the assessed diaries to students before the next lesson, Sampling Snoops.

17. Homework assignments can be utilized as the teacher deems necessary to provide additional formative practice for the student.

#### Assessments

Formative assessments
1. Students respond to the prompt (Entry #2). Formulate a hypothesis about what you think will happen in each of the physical science experiments. Write these hypotheses in your diary.
2. Students respond to the prompt (Entry #3). Students formulate a hypothesis and design an experiment to test how much time the average eighth grade student should spend on homework per week to make good grades.

Formative assessment:
1. Students follow-up Detective Diary #2 with a response to the prompt: After seeing the results of the experiment, evaluate your hypothesis from Detective Diary #2 for each experiment by making inferences and drawing conclusions based on observations from the demonstration. Were your assumptions on target? Did you consider all of the variables in your hypothesis that shaped the outcome during the demonstration?
2. Criteria for successful completion of the Detective Diaries:
(a) Check student responses using the Experimental Design Rubric. (See page 3 of the Associated File.) Provide specific feedback for students regarding their responses to each prompt.
(b) Use the Long-Answer Question Rubric to evaluate the thoroughness of the response. (See Unit Plan Associated File. Further information is available in Extensions.)

If using the Unit Plan: Statistical Sleuths, return the diaries to students before beginning the next lesson, Sampling Snoops.

#### Extensions

1. The Beacon Unit Plan associated with this lesson can be viewed by clicking on the link located at the top of this page or by using the following URL: http://www.beaconlearningcenter.com/search/details.asp?item=2958. Once you select the unit’s link, scroll to the bottom of the Unit Plan page to find the section, Associated Files. This section contains links to the Unit Plan Overview, Diagnostic and Summative Assessments, and other Associated Files (if any).

2. To offer a more real-world learning experience for students, consider allowing them to actually survey the students in their school.

3. Allow students to peer–assess each other’s diary entries if they are at a point where they can assess the content accurately enough to provide effective feedback.

4. This lesson could be used in the beginning of the school year in order to review or prepare students to learn the scientific method.

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#### Attached Files

Designing Detectives Associated Files.     File Extension: pdf