I read somewhere in some thread about math and "going deeper instead of higher". How do you do that at elementary levels? I mean, adding and subtracting can only go so deep. Then, you pretty much have to move on to bigger numbers and multiplication and division? Or, am I missing something?
Yes, you need to move on to bigger numbers, multiplication and division. You are completely right, you can get only that far with addition and subtraction. Once you cover multiplication adn division things get more interesting, you can do Zaccaro, you can also look into Singapore Challenging Word Problems (3 and up. I wouldn't really bother with the lower ones).
You can also do things like Venn Perplexors, I suggest LevelB (3rd-6th grade). You don't even need multiplication or division for this. Kriston, your son may like it.
Of course we still add new concepts in like prime numbers, addition of fractions, geometry, ... It's pretty much unavoidable, but like I said you can go deep from a certain level and give them problems which will require some effort.
