More Hover Puck

 

33 Today we played with the hover pucks some more, this time with the help of some skinny rubber bands tied together. We discovered that if two rubber bands were pulling equally in opposite directions and one let go, the puck would go towards the one that didn’t let go. We also discovered that if you try to use the rubber bands to LIFT the puck, they stretch really really far…much farther than they stretched when we were pulling the rubber bands horizontally or at an angle. ¬†Additionally, if you pull a hover puck with one rubber band and expect it to go at constant velocity, the rubber band will go slack as you try to maintain constant velocity.

By the way, in this photo the puck is not turned on, so it is at rest on the floor. A student is pulling with a rubber band but not enough to make the puck start moving.

 

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Hover Puck

32 Today we all sat on the floor and played with the hover puck. Each class made observations, and we talked about interactions. Today was the first time students saw an interaction diagram. It was a first for me, too. I have never used them. I think they started being used after I took Modeling Instruction workshops in 1997-98. Anyway, the students seemed to think it makes sense as written.

I praised the student who said it sounds like there is a fan inside the puck, since we could not see the fan so it is not a direct observations. We also checked whether the puck could be said to “float” by sliding paper underneath. One class wanted to send the puck all the way down the hallway, so we did that.

 

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Weight vs. Mass

30 The conceptual students are finding the relationship between weight and mass. This is two classes’ worth of data, so 12 groups, each with 6 objects to measure mass using a triple-beam balance and weight using spring scales. I made this graph, but my students had to graph by hand and did not have to determine uncertainties in the slope or y-intercept. I did that for my own pleasure.

Today was a strange day because we administered PSAT/NMSQT tests to all the 10th and 11th graders, then we had periods 4-8. Tomorrow we have a half-day followed by inservice, and will meet for periods 1-4. During 4th period, I have hall duty. I don’t mind having hall duty twice for each of my other classes meeting once, since this means I don’t have one class getting absurdly ahead of the others. However, due to this wacky schedule, I am not assessing my conceptual classes this week.

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