OpenSciEd Unit 8.1 · Lesson 08 · 8.A
Modeling Other Force Interactions
Assessment guide
How to read student work on this assessment — standards alignment, what strong understanding looks like, and common gaps.
Standards alignment
What understanding looks like
Strong
- Q1) Draw and label two free body diagrams showing the contact forces between the box and the cart as they are moving together at time 4.
- Q2) Besides the cart, what other objects or subsystems is the box either making contact with or colliding with at time 4?
- Q4) Do you think these kinds of forces are also acting on the cart as it coasts down the track at time 2? Why?
- + Friction would be acting on the cart wheels, but they aren’t sliding over the track like the box and there is less surface area in contact with the track, so there would be less friction on the cart from contact with the track than on the box from contact with the track.
- Q5) Where does this tell you some of the energy in the system might be going as the box and cart move down the track??
- + Some of the energy might be transferred to the air.
Emerging
- Q5) Where does this tell you some of the energy in the system might be going as the box and cart move down the track??
- + Some of the energy might be transferred to the air.
From Teacher Edition
View assessment opportunity →Facilitation guidance from the lesson plan — what to notice in student thinking and how to respond while teaching.
Building towards
8.A Develop and use a model to identify other parts of the system the cart and box are making contact with or colliding into that could be producing contact forces on these subsystems, causing energy to be transferred to or from them as the box and cart travel down the track.
What to look / listen for
See Key for modeling force interactions in the launcher, cart, box, and track system for guidance on what to look for.
What to do
Treat this as an informal assessment of prior knowledge related to how forces from friction and air resistance act on moving objects. Do not correct preconceptions at this point. Make a copy of student responses on Modeling other force interactions in the launcher, cart, box, and track system so you can return the original to students to revise at the end of the next lesson (Lesson 9) as a home-learning assignment. This will provide you a reference to compare student thinking before Lesson 9 to what they are thinking by the end of Lesson 9.
Materials
Last updated from official OpenSciEd on 6/5/2026
Student handout
8.1 Lesson 8 Handout Modeling other force.docx
Google Form
Digitized — add an editable copy to your Google Forms
Teacher guide
8.1 Lesson 8 Teacher Edition.docx
Answer key (recommended)
8.1 Lesson 8 Answer Key Key for modeling.docx