I am really loving linking interaction diagrams, free body diagrams, and equations in Balanced Forces. Tomorrow I will have the students do this same problem except treating both blocks together as a single system.
I’ve seen and played with Edmodo before. What I didn’t realize what that, unlike many other LMS’s, the iPad app is fully functional. We have a number of iPad cart pilots that I am helping with in my role as a tech integration specialist, and one of the huge problems has been ways to get work produced by students on apps into a teacher’s hands, particularly because the iPads are not 1:1 (as many as 7 students use one iPad on a given day, so they cannot have one student’s login information as would normally happen with an individual iPad). Edmodo may be our solution, as students can upload, at the very least, items from the photo roll and Gdocs to posted assignments.
My 2.5 year old son valiantly tried (for the first and last time) to escape from his crib on Saturday and broke his arm, and it had to get set today. Thus I was not at school. Above is the exact copy of the sub notes for today. I love how many times I was able to put “They will know what to do” and mean it. I am exited for tomorrow to see how they did!
Today we whiteboarded the balanced forces WS 1. The problem above spurred a conversation about how we know the forces balance (they must, since the velocity is constant, right?), at which point I prompted the group to draw the dotted lines (A new term, components!), label them, and then use them to write an equation. I found this a thrilling way to hint at Newton’s 2nd law (and to represent Newton’s first). Additionally, both classes got into a great discussion about a block being pulled across a table with friction and whether tension should be bigger than friction, both with CV and not CV. 7th hour didn’t resolve it when the bell rang, we’ll be coming back to that tomorrow!
I generally have groups of three, with a few groups of two. They work together through a unit, then I switch the groups. I had the groups members number 1 through 3. I had them work through the problem (whiteboarding yesterday’s Modified Atwoods situation, where we drew Interaction Diagrams and Free Body Diagrams for each of the three sections of motion; at rest at the beginning moving with the rope pulling the cart, then moving after the weight has hit the ground so that the rope is not pulling (much) anymore). Anyway, after they completed the problem I had the 1’s move to the right and the 2’s move to the left, with the 3’s staying put. Thus there was an original member of the group, who ended up essentially trying to defend what they had done, with two new group members who then added their perceptions to that particular board. They made changes to the board in a different color than the original board. Then I nominated a group (usually one that had a particularly interesting discussion going on) to present, and we came to consensus that way on the first section (at rest). This was mostly to make sure that everyone was on the same page and we didn’t have any rouge groups.
I had them move again (again only the 1s and 2s) and then simply modify what was already there to now represent the second section of the motion. Then they moved again, edited again, and a group presented. Repeat one more time for the last section.
In Kelly’s and Sophie’s version all the students end up working on work that is not their own; in mine I had students who stayed rooted to their original work. I see value in both and plan on trying their version next time around to see what I think. I also liked that this sped up the whiteboarding process; I don’t think we needed to have a whiteboard meeting for each of these three scenarios. We were able to get through this and move on to start whiteboarding the next worksheet in a 45 minute period.
Today we finished up the process of discovering Newton’s First Law through interaction diagrams and free body diagrams. We then took velocity vs time data of a modified Atwood’s Machine, where the cart is first at rest, then being pulled by the rope, then coasting when the mass hits the ground. Tomorrow we will whiteboard interaction diagrams and free body diagrams for these three sections of the motion. Thanks to Matt Harding for the idea to do this!
Today we jumped into drawing Interaction Diagrams and Free Body Diagrams. Tomorrow a pattern emerges.