January 07, 2010


I mentioned in a previous post, REASON WE HOMESCHOOL # 4, that we were taking a detour from our plans to jump on a teaching opportunity inspired by a gift for Mason.

Today we began that detour by talking about speed and acceleration while testing our marbles.   First we observed with our eyes.  We lined up a glass and metal marble and released them on the track.  On the inclined plane the metal marbles were definitely faster than the traditional glass marbles. However, once the track was level with the floor, the differences were harder to see.

Our second test today was measured with a stopwatch.  We measured the time it took for a metal (M) and glass marble (G) to travel the length of the coaster track using an included plane for acceleration.  We started our descent from 4 inches off the floor, and then  moved our starting place higher off the floor by 1 inch at a time and recorded our findings.  We took 12 measurements per marble.  Here are a few of the recorded times:

Time taken to complete the track
4 inches off the floor =  (G) 5.09 secs  (M) 5.06 secs
24 inches off the floor = (G) 1.75 secs  (M) 1.60 secs
44 inches off the floor = (G) 1.15 secs  (M) 1.12 secs

As you can imagine we had to do several runs to get a "more accurate" reading due to fingers getting in the way, marble drops and Mom's user error of the stopwatch.  Godzilla visited Tokoyo during our testing as well, when our dog laid his nose on the track and stopped the marble with it. ☺ 

After our experimenting today, Mason was able to create enough speed to successfully travel through his double loop!  HOORAY!


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