A while back I got these sort of cool spring-loaded multiplication and division matrices by Lakeside. (I’m guessing that they also make ones for addition and subtraction.) Leo likes just popping the cubes in and out, and occasionally actually reads the answer.

Today I noticed that the two together in a certain configuration look like the battleship game, so we made up a fun new game called mathematical battleship. You can tune the rules as appropriate to the age and skill level of your child, but these are the ones we played this morning.

Each player gets one board and sets up his fleet by popping up the positions for his ships. We played with four three-long ships. So Leo popped up four ships (twelve cubes in all), and I did the same on my board. In a perfect world we might have the same board, but since I only had one multiplication and one division board, we each had to take one. I tried to get Leo to take the division board so that I would have to do the division problems, but he didn’t quite get that the *opposite player has to do the problems on your board*, so he insisted on taking the multiplication board, and so he was doing division problems, and I was doing multiplication problems. All the better!

So once we each have created a secret fleet of four three-long ships, we start the battle. Player 1 says “Fire!”, and player 2 has to ask player 1 a problem from one of his ships. If player one gets it right, then player 2 says “Hit!” and pops in that cube. You can figure out the rest. Of course, I can do all the problems on both boards, and Leo, having insisted on my having the division board, had to do division problems (!), so I simplified his problems by putting my fleet near the top of the board, where the divisions are simpler, and I made a few intentional errors (and, one ACTUAL one!) in my multiplication. The upshot was that he beat me once and I beat him once, and we tied once.

Obviously, as I mentioned above, you can tune the rules as appropriate to the age and skill level of your child.

[Footnote 2014-11-4: Turns out that there’s more strategy then I though to this game! Leo wanted to play again last night, and this morning, and discovered that in certain cases, esp. when the ship is horizontal or vertical, the answers are either all the same, or increment by n. I’m not sure that he has this strategy completely clear, but he told me in one case, “Hey, it’s the same!” and thence guessed at the next one…correctly! I’m afraid that he’s going to realize that he can just read off the answer to my problems from his board; but he hasn’t figured that out yet! 🙂 ]