Projectile Motion: Barbie Drop

This is my second activity on projectile motion.  The first activity (on the missing airplane) is here.

Students came into class and were greeted by Barbie up close to the ceiling.  It took between 10 seconds and 5 minutes for a student to find Barbie.  One student immediately knew what we were going to do:

Mr. Winfield – Are we going to drop Barbie?

Yes, yes we are!  See, I’ve always wanted to do NCTM’s Barbie Bungee but I’ve never fit it into my scatterplot lessons.  So instead, I decided – let’s change the math and DROP her!

Why should we drop Mermaid Barbie?  Students were immediately able to tell me we could figure out how long it would take to hit the ground using the math we know.

We began with estimating her height and her drop time.  One student who is over 6 feet tall became our human ruler which was rather ingenious of them.  Then, instead of measuring, I gave them the accurate answer for Barbie’s height.  I missed out on another great opportunity to get students involved in every part of the lesson.  Students then created their formula and found how long  it would take for barbie to fall (0.733 seconds)

Now, the math isn’t real unless you drop Barbie.  We brainstormed roles we needed – timers, droppers and I wanted a videographer.  One person from each group got to drop Barbie.  Everyone else who had a phone was timing Barbie’s fall and one person was using my smart board.  I was in Google Docs making a spread sheet of times.

After a dozen drops between the two classes who were able to do the activity we had an average of 0.68 seconds and I deleted some of the bigger outliers before doing the math.  I’d say we were pretty close to Barbie’s predicted drop time.

We were able to end our discussion with possible reasons for error in our results.  Once again, I could have pushed deeper.

Next time, I’ll be better prepared.  I see this as a HUGE opportunity to push the math, understanding and application of the quadratic formula.  Next time around it’ll be better – guaranteed.

What went well:

+ So many students were ready to drop Barbie and add to our data set.

+ Some people botched their drops so we were able to decide if we should keep some of the messed up attempts and WHY.

+ Students were talking about math class in other classes – what more could you want!

What I’d Change:

– Everyone got the same answer for their prediction.

– I could have pushed more work on students – averaging, prediction, measuring.

– I forgot my iPad that day so I don’t have a video. A student recorded in both classes, but I’ve yet to get the videos :/

Barbie is still hanging out in her “Bath tub” 8.625 feet in the air.  I’ll post a picture soon.


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