OpenSciEd Unit 8.1 · Lesson 05 · 5.A
Mass, speed, and collision outcomes
From Teacher Edition
Facilitation guidance from the lesson plan — what to notice in student thinking and how to respond while teaching.
Building towards
5.A Plan and carry out an investigation and identify patterns in the data collected from the investigation to provide evidence that peak contact forces on each object during the collision are equal in strength and the strength of those forces increases when the mass or the speed of the object that was moving before the collision increases.
What to look / listen for
Identification of a single independent variable
mass or speed
Identification of the following dependent variables
the peak force measured on the push-pull spring scale on cart subsystem A and the peak force measured on the push-pull spring scale on cart subsystem B
Identification of important variables to keep constant
If students identified mass as the independent variable then they should identify speed as an important variable to try to keep constant. If students identified speed as the independent variable then they should identify mass as an important variable to try to keep constant.
A data table with results from at least two conditions tested (e.g., no additional mass vs. added mass or slower speed vs. faster)
Peak forces measurements and/or equalities or inequalities noted for both push-pull spring scales for each condition tested
Results from repeated trials for each condition (optional)
Source(s) of error in the system (optional)
What to do
You may want to have groups check in with you before moving to their labs to collect data. This would allow you to determine if the group members have properly considered 1-4 before carrying out the rest of the investigation. Once all groups are collecting data, you can then attend to whether groups are correctly recording data for 5 and 6. If time is short you could assign something related to 7 as a home learning assignment or extension opportunity, along with a question asking about ways to redesign the system to improve its reliability in terms of generating consistent results, eliminating more of the human error, and/or better controlling for speed if mass is the independent variable. This may lead students to propose ideas that are similar to what is in the procedure for the first investigation in Lesson 7 and can give you an opportunity to assess student thinking around engaging another part of the practice of planning and carrying out an investigation: revising an experimental design.