Reviewing the graphs students saw in Investigation 4.1 and asking them to label the motion on the graphs was really helpful. There are students who confuse the position-time graphs and the speed-time graphs; and this seems to be most effectively dealt with on an individual or pair basis. Asking students to explain why they labeled the horizontal line as traveling at constant speed (on a position-time graph) has revealed that some describe no motion as constant (non-changing) speed, and some interpret the horizontal line as the object has motion and is traveling at constant speed.
In Investigation 4.2, students seemed to adjust easily to the error in the directions (I claimed 
responsibility for the error) so that they were looking at speeding up data in the first part and slowing down data in the second part. Getting the equipment right for the acceleration graphs takes patience; students can definitely do some of this - they should be able to accurately predict what speeding up ought to look like on the speed-time graph. Here's the best slowing down graph I collected.
responsibility for the error) so that they were looking at speeding up data in the first part and slowing down data in the second part. Getting the equipment right for the acceleration graphs takes patience; students can definitely do some of this - they should be able to accurately predict what speeding up ought to look like on the speed-time graph. Here's the best slowing down graph I collected.Wendy's post suggested several trials and looking at best fit interpretations. Here is her set of graphs for slowing down:
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