# Day 11: Whiteboarding Archimedes’ Principle and Magic Marker App

Today was the first problem-focused whiteboarding session of the year today in AP Physics 2. I think it is a good sign that it is the eleventh day of school and it is the first day that we are plugging numbers into equations in class. I’m being very deliberate this year in the problems that I choose for us to whiteboard in class. I’m trying to select problems that integrate multiple concepts and lend themselves to clarification and extension questions. This was a good whiteboard for the first problem:

The problem using the Siri equation and Archimedes’ Principle to estimate a persons body fat percentage. I modeled a sample extension question by asking the group, “if the person was submerged in oil instead of water (ick!), would the weight underwater increase, decrease, or remain the same?” I then followed up with a challenge when the group responded that the buoyant force on the person would change by asking, “but yesterday we said that the buoyant force on the hydrometers were the same in all fluids. Can you remedy this apparent contradiction?” I’m trying to coach the students into using these whiteboard problems as prompts for conceptual questions that require careful reasoning and justification.

While students were whiteboarding, I tried the new Magic Marker app from Instructure to track three outcomes:

1. prepared before class
2. effectively presents whiteboard