AP® Physics: The Scaffolded Block Scenarios, Part 2

This is a follow-up to my previous "scaffolded block scenarios" post.  This week I started these investigations I made late last year and I LOVE THEM.  The kids are responding so well!  We've worked through the "Block on a Ramp" study and started the "Stack of Blocks" study using a mixture of desk-boarding (expos on desks!) and whiteboarding.  Side note:  I use desk-boarding when I don't feel ready to release them to the openness of the whiteboarding experience.  I often do this at the early stages of a unit when I want to make sure they're incorporating the formalities of problem-solving into their work (picking a system, identifying the coordinate system, etc.).
block on a ramp study physics education DiSanto

What have I seen so far?

  • The students applied Newton's Second Law on the FIRST DAY of our forces unit!  What?!?  Usually, it takes a few days of gearing up!  Getting enough in-class practice has always been a struggle in this advanced course (so much content...too few classes...sigh).  I love that we could dive right in and give things a go!
  • The students quickly connected that a system at rest and at constant velocity look very much the same on a free body diagram.  Lots and lots of discussion there.  I'm sure that will continue for weeks to come.
  • Discussions about: normal force (why? what direction?), defining a system, drawing the forces felt by not exerted by the system, the benefits of solving problems without numbers (you can check your units to see if your answer even makes sense!), and when to include the sign of  force.
  • The nuances of friction were definitely the main focus (as noted in the original post) and this was abundantly clear to the students.  One student brought up a great point that not all of these scenarios could be true for the same ramp/block set-up.  Something has to change...the angle, the interfacing materials, something... So good!
  • The need for a rotated coordinate system on the ramp scenario was also made abundantly clear quite early and they picked up on the need to align one direction with the acceleration of the system.
  • With the stack of blocks, they are starting to see the interactions between objects and how to model it.

What am I hoping to see as we continue?

  • I want to see the students make connections between two different sets of action/reaction pairs.  This will be very hard for them and this is the earliest I've ever had them tackle it.
  • I want to see the students realize that the chosen system leads to very different free body diagrams.
  • I want to see the students tackle our shared set of problems in the packet after these studies are over with confidence.
  • I want to see the students become more comfortable learning with the support of their tablemates.  This one is more of a norms thing.  As we're still early in the year, the students really just want me to help them all the time and tend to forget about the wonderful resource they have in each other!
I'm entering the weekend quite optimistic and excited to tackle more block stacks next week!  I'll keep reflecting on this series of problems and see if there's anything I want to change for next year.


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