Adding and subtracting decimals has been a bit of a sticking point for my students. It isn't that they don't get that you have to line up the decimals....they really do. But when it comes down to it, they seem to be a little stuck there. When I give them numbers such as 4.5 + 3.4, they are golden. But when they get 12.3 + 4.52...all heck breaks loose! And don't even think to throw a whole number in there! OY!!
So I came up with this little "game" (that, truth be told, really isn't a game, but I called it a game and my students were hooked ;) )
I created a little game board on a piece of construction paper. It had 3 decimal slots, a + and a line. That is it. Then I cut up about 15 cards and wrote decimals with varying place values on it.
They ended up with a math problem that looked similar to this.
Done and done. And I can't tell you how much my students enjoyed it! They also really saw how the decimals matter in the problem.
Simple, effective, and cheap :) My kind of math game.
What do you do to help your students remember to line up the decimal?