Unit 3 Constant Acceleration Particle model.

Paradigm lab:  We began the discussion of unit 3 by asking what we can measure with a cart on a ramp. Seeing how it is different from the constant velocity car.  We came up with a question "What is the relationship between the position and time for a cart on a ramp?"

The method was going to involve marking on the track.  It was discussed that it is beneficial to have the students chase the carts and make marks to experience the acceleration so do this without the motion sensors.  The lab was done and then the boards are compared.  The fit that was used was variable power.  Our first point was not the zero position point so we resolved that issue.  The coefficient on the x^2 terms were compared and there was a question as to whether the angle was the difference that we saw in the groups so our group compared the angle and coefficient. 

In the analysis

·         Since we have already come up with the idea that the slope of the d-t graph is the velocity we use the slopeometer (two markers attached together) to find the velocity and construct a v-t graph

·         Discuss changing velocity (slope of v-t graph) and then relate that concept to the everyday definition of what we know as acceleration

Then 4 situations are given and have different groups graph different ones and use this to have the students hash through the idea of when is acceleration positive and when is it negative.

Things top note

• Point out sensor thinks it is zero
• From the discussion the idea of acceleration meaning speeding up or slowing down.
• Speeding up slowing down dance
• Deal with acceleration at points where the car is at rest.
• Add acceleration to the motion maps using symmetry for the slowing down speeding up ones

Develop equations using a v and x from groups equations.  This was very powerful I thought in showing the relationships.

Use the spheres rolling down the ramp at different points and at the same points at different times

Make it easy and give them multiple choice.

Give them a d-t graph and have them come up with the v-t graph and then show a ramp that would yield that motion.

Constant acceleration particle model synopsis.

Area under V-t graph

Slope of v-t graph

Equations

Practicum  Marble rolling across seats given a constant velocity cart, ramp with marble.

Here are some extras that came out of this units discussions

• Handling homework—have groups sign up and work them out on the whiteboards and discuss
• Come at the model through conversation but make sure to give the model as a whole
• “check with your neighbor” as a means of getting students more focused.
• The units in the equations can be very confusing for the students

I think this will go well.  It is definitely more complex than the CVPM.  There are a lot of intricacies that I will have to make sure I remember so I will need to make sure that I have questions written down ahead of time.

Implementation

I have 10 1.2 meter  tracks  I can come up with a way of connecting them together which will give me 5 2.4 meter tracks.  I would like to keep my lab groups to 4 which means I could have a class of 20 (possible but not very likely.  I also have an air track so that could get me up to 24.  I am more likely to have 30-32 students.  I might have to go up to lab groups of 5 but that sounds like an engagement problem just waiting to happen.  I could go with the shorter tracks but that will mean fewer data point especially for the intro lab.  It is not as big of a problem with the motion detector part.

The biggest problem that I can see is just equipment issues especially regarding class size.  Lab groups that are too big leads to some students not being engaged.  Also the individual student desks that I have are not the greatest but they are definitely movable so I think it is workable.  As I mentioned before I think that there will be support from the school administration since this follows really well with a lot of the PD that we have had this past year coming from the ICLE (International Center for Leadership in Education) and the Charlotte Danielson framework for evaluations which our school has been using for the past two year.