Describe how energy passes from one object to the next in a chain of collisions or contacts.
Energy does not always stop at the first object it reaches. It often passes along a chain, moving from one object to the next like a message passed hand to hand. A row of falling dominoes is a chain: the first domino falls and bumps the second, the second bumps the third, and so on, with energy moving down the line.
A chain reaction stops when there is a gap or when the energy runs low, spread too thin to keep the chain going. Watching where a chain breaks is as useful as watching where it succeeds, because it shows exactly how much energy each transfer needs to keep moving.
Mastery looks like: They can describe, step by step, how energy passes from object to object in a chain, and explain why a chain can break partway through.
Common stumbles: Thinking new energy appears at each domino instead of being passed along from the one before it; not noticing that a chain needs enough energy to bridge each gap.