In some of our work during the last week I noticed that my younger son was having a little difficulty with the distributive property. Part of that difficulty seemed to be coming from confusing multiplication and addition. I actually remember being his age (3rd grade) and having some similar difficulty with addition and multiplication, so at least I’ve seen this type of confusion before.

Because this confusion seems to have come up recently on a subject that I think he’s pretty familiar with, I’m not worried that there’s some deep problem here – he just needs a little practice to shake off the rust. We turned to Khan Academy for that practice.

I wasn’t able to find exactly what I was looking for, but I did find this set of exercises which seemed to be close enough:

Khan Academy’s “Order of Operations with Negative Numbers”

As I was expecting these exercises gave him quite a bit of trouble. In fact, the first time around it took him 26 exercises and roughly 30 min to get 5 questions in a row correct (his count, not mine, btw). We worked through a few more last night and then some more this morning, and it seemed as though some of the difficulties got ironed out.

Here’s the last 5 exercises from this morning:

So, I’m happy to have Khan Academy’s problem bank around to use in this type of situation. Here I had a subject that he seemed to be comfortable with previously that was suddenly was giving him trouble. That trouble was making learning a new subject more difficult than it should have been, and taking a break to review the old subject seemed to be important.

Having 1000s of problems in a wide variety of subjects at my fingertips makes taking breaks like this really easy – almost effortless, really, as I’ll I have to do is find the right section. With the arithmetic difficulty (hopefully) behind us, I’m excited to return to studying a little bit about circles tomorrow.

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And you are doing negative numbers with a third grader???????????????????

This sounds very familiar. My older son is also in 3rd grade and we’ve been doing AoPS pre-algebra at home (in small increments). The distributive law was also a problem paritcularly last year and we had to come back to it several times over several months for it really to stick.