# Day 17: Weight & Acceleration Practical

Physical Science: Weight

Today began with some talk about the engineering design process developed by EngrTEAMS. In particular, we placed ourselves in the “Learn” phase since students agreed they need some new science to understand crashes. I introduced forces as a tool for understanding crashes, and we dove in to a lab where students used spring scales to measure the weight of several hanging masses, then graphed the results. Tomorrow, we’ll get to the idea that the slope is the strength of gravity.

Since the lab is fairly straightforward, I had the chance to do one-on-one conferences with a few students who currently have low grades to make an action plan. I’m taking an “SBG-ish” approach in the course, which means I enter unit tests in the gradebook, rather than standards, but the tests are nearly all of the grade and I allow retakes to replace the initial score. I really liked that this freed me to talk with students about missing skills and understandings, rather than a long list of missing assignments. The students also seemed much more positive about these conferences than in the past.

Physics: Acceleration Practical

For most of the hour, students started working on a lab practical where they will roll a marble down a ramp so that it lands in a tumble buggy as it drives past. As a class, we collected the data students need to get the speed of the buggy and the acceleration of the marble, then students drew a random starting position for either the marble or buggy. I introduced the practical very clumsily in my first class, so I’ll need to do some clean up and clarification when we get back to the practical on Friday.

The first part of the lesson was finishing yesterday’s whiteboard presentations and produced one of my favorite moments of the day. When preparing their whiteboard yesterday, one group made the very common mistake of using v = d/t to find the final velocity of an accelerating object. In their quick conversation, they realized their answer didn’t make sense with the other values and were able to correct it. That group was brave enough to share that mistake, as well as how they caught it, when they presented the problem.