OpenSciEd Unit 8.1 · Lesson 01 · 1.A
Initial model: objects in collisions
From Teacher Edition
Facilitation guidance from the lesson plan — what to notice in student thinking and how to respond while teaching.
Building towards
1.A Develop a model to describe interactions between two objects as they collide and show the changes that occur in the structure of both objects when one object is damaged as a result and also when neither object is damaged as a result.
What to look / listen for
Unobservable mechanisms
Prompts in this task ask students to engage in two elements of the modeling practice related to representing descriptive aspects of the phenomena as well as unobservable mechanisms (energy transfer in collisions and objects pushing on each other when they collide). You may also see some students using particle-level representations to help explain changes occurring in the objects in the collison, based on their extensive work in developing such models in prior OpenSciEd units.
Factors or variables that cause the materials to break or not break in a collision, such as mass, speed, area of contact, material type and thickness, any other structural differences students wish to identify
Other connections to CCCs
There are phrases in the prompts that ask students to consider connections to related elements of CCCs, particularly cause and effect, systems and system models, and stability and change. These may lead students to develop and use ideas that help them connect ideas about forces, energy, and changes occurring in the object. These ideas will be developed later in this unit. Here is a good opportunity to see if students are already making some of these connections:
- In a collision objects exert forces on each other; those forces cause energy to be transferred (effect) to or from the objects.
- Each object in the collision (subsystem) exerts a force on the other object in the collision; these forces are equal in strength and opposite in direction.
- These forces (cause) also result in some deformation (change or effect) of each object.
- An object’s structure (the type of materials it is made of and the shapes of those materials) affects how much it will deform and how much it will push back in a collision before breaking.
- Deformation beyond a certain point results in damage (a permanent shape change); but deformation below that point does not (stability).
- The amount of kinetic energy objects have in a system is related to the amount of energy that can be transferred between them and the amount of peak force they will apply to each other in a collision; the amount of kinetic energy is related to the mass and speed of the object.
What to do
If students do not include connections to any of these ideas listed above, that is OK for now. Students will build on and revise their models over the course of the unit. Make a copy of these explanatory models and compare them with what students show in their individual model and explanation at the end of Lesson Set 1 and the end of Lesson Set 2. You may also want to have students analyze their growth by comparing these artifacts related to the elements mentioned above.