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Saturday, January 07, 2012

Missing the point

So I just spent about half an hour writing some variation of the same theme on 18 notecards. The main idea was "We saw in our experiment that gravity pulls things down at the same time." 18 out of 19 notecards in my afternoon class.

This week, the science focus has been gravity. I started by showing the kids three water bottles of the same size but different mass. One was empty, one had wet paper towels in it, and one had sand in it. They were labeled, respectively, lightest, medium, and heaviest.

I had them write a prediction for what order in which they would hit the ground if they were dropped at the same time and from the same height. Most of them said the heaviest would hit the ground first. This seems intuitive at that age. Some of them said the lightest would hit the ground first, and qualified that by saying that since it didn't weigh as much, it could move faster. OK, there are no wrong hypotheses, after all.

But then the kids did their own experiment involving three different items of varying mass. They dropped the items repeatedly at the same time and saw that they all hit the ground at the same time. We discussed afterwards how items hit the ground at the same time due to gravity. I told them that if we went up to the top of the school and dropped a bowling ball and a grape at the same time, they would hit the ground at the same time. I even held up a tiny eraser and the big thick math textbook and dropped them, and (GASP) they hit the ground at the same time.

So yesterday, for their test (AKA "Reflection"), I showed them 3 items with varying masses. A big heavy Baby Care book that a fellow teacher had loaned me (the kids found this hilarious; one girl even snorted, "HA! BABY!"), a mostly empty water bottle, and a little binder clip. I identified them as heaviest, medium, and lightest. I then asked them to write, on the index card, what order the items would hit the ground in if dropped at the same time, and to explain their reasoning.

One girl, out of nineteen students, wrote that they would hit at the same time because that's how gravity works. The other eighteen wrote some staggered order, most of the explanations being that the more mass an object has, the faster it will fall.

Wow.

I really hope a lesson on magnetism is coming up soon, because at least then SOMETHING has a chance of "sticking" in my class.

6 comments:

Candy said...

... and this is why we have teachers like you. I'd beat my head up against a wall after a while. It's like they aren't even listening. Well... one was... so, what? <5%? Woot!

Kathy said...

I feel your pain! That would be my entire class this year! At least you got one who listened and learned!!!

Mister Teacher said...

Surprisingly, my homeroom - who typically are 5 times more unmotivated to listen - did much better. Out of those 18, I think I only had to write the note about 9-10 times!

Angel Read said...

That kind of reminds me of that part in one of the Wayside School books where the teacher drops the computer out the window to teach them about gravity. Maybe you should try that next!

Anonymous said...

I had several answers along the lines of...."they will all land at the same time because of gravity and it doesn't matter what the mass of the object is BUT because the mass of the book is bigger and the fruit loop is less then the book will land first and the marker next, then the fruit loop will land last because it is lightest" !!! I obviously have some misconceptions to clear up.
kp

Mister Teacher said...

LOL. Misconceptions AND lack of confidence in their opening statment!

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