Exploring a Hypothesis

The cartoon demonstrates what can go wrong when a procedure is imprecise.

Ask:

What went wrong?

Have students write a more precise procedure for making a peanut butter sandwich.

Share some of the elements of an explicit procedure, including detailed directions for each step so that nothing should go wrong. Students may want to know how specific to be. For example, is their user someone who is not at all familiar with the concept of a sandwich and has never seen a loaf of bread or a jar of peanut butter? You may want to tell your students to design the procedure for someone who is familiar with all of the ingredients but has never seen a sandwich.

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Tell students that in the peanut butter sandwich activity, they practiced thinking about all the steps necessary to successfully complete a task; however, precision is not completely necessary when making a peanut butter sandwich.

Paraphrase:

When we design a procedure for science, we need to include:

• detailed directions for each step
• the number of times the procedure needs to be repeated
• how to record the data
• units of measurement that are explicit

Students evaluate Maria’s procedure for the four criteria. Engage students in a discussion about Maria’s procedure.

Sample responses:

• Maria gives detailed directions for each step.
• She did not include the number of times that she is going to repeat the procedure.
• She does not say how much salt should be placed on the ice cube.
• She is careful to include labeling in her procedure.