Here are two lab practicals my colleague and I wrote to end the unbalanced forces unit. Our goal was to give students a task with clear objectives and lab skills they’ve already built. Even better are tasks with an intriguing hook. I was thrilled to bring back the Tumble Buggy for the third time this year. Can I work it in for the last few units?

I designed my practicals to be submitted individually, though students worked with a partner on data collection and problem solution. The rubric is embedded in the packet so students are aware of expectations.

The Wrecking Crew: Drop the Wrecking Ball onto the Buggy. The Wrecking Ball is part of a Half Atwood machine, so harkens back to a lab we did earlier in the unit. After half a year measuring Buggy velocities, there is a huge range of quality and efficiency. Allocate 90 minutes to 2 hours in class.

Update, this 0:22 clip shows three different groups hitting their target.

The Elevator Problem: Find the acceleration of the elevator using only a force sensor. This practical calls on prior knowledge from us riding in the elevator to solve for net force and then a set of problems from the Modeling Instruction materials. The aspect of this Practical that I find interesting is how little equipment is needed. Allocate 70 to 90 minutes in class.


  • 9th grade physics
  • Modeling Instruction-ish curriculum
  • We’re at the end of all of motion and forces

Class management tips:

  • Put half the groups onto each task per period. Swap the next day.
  • Demonstrate each Practical to the whole class so they understand the point.
  • Divide each Practical into chunks to aid in student problem-solving and independence.
  • If using the Vernier Bluetooth carts, assign a color to each task, so that you can monitor the tool restrictions (for instance, one group was permitted use of the scale and the other wasn’t).
  • Refuse to answer physics questions if at all possible. I’m happy to help them operate the equipment, though.
  • Offer a second-chance section for performance-oriented Practicals, such as Wrecking Crew. This is a chance to explain the solution more fully and explain exactly what went wrong.
  • Be clear about your academic integrity expectations before starting.

Borrow if you think these would be useful. I’d love to hear about variations on this theme, too.