A lucky save courtesy of Khan Academy

We are in the process of moving right now and I discovered last night that I accidentally moved the math books up to the other house. Whoops!

Because of that goof up by me, this morning I had my older son play around with spheres, cylinders, and cones on Khan Academy. Turned out to be a lucky break as those exercises revealed a little gap in his understanding that I hadn’t noticed previously.

The exercises themselves aren’t necessarily super special or anything, but they were different enough from the exercises in the Art of Problem Solving book to reveal this little gap. The problems he was working on were from this section:

Khan Academy problems on volume

The slight difference between this problems and the ones in our Introduction to Geometry book was that (most of) the problems asked you to round the answer to the nearest integer. One of the answers was something like \frac{100 \pi}{3} My son first rounded 100 / 3 and then multiplied by \pi on this one.

It was interesting to see the difficulty he had seeing \pi as a number rather than as a symbol. I’m happy that these problems from Khan Academy helped me discover and address (hopefully!) this issue.

Here’s the last problem we did this morning.

So, a fun and instructive morning for both of us. Lucky to have a positive outcome arise from leaving the math books in the wrong house!



One Comment so far. Leave a comment below.
  1. What a strange glass ! Not for drinking from ! Maybe Khan changed inches to centimeters and forgot the scale factor.

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