Cognitively Guided Instruction is a great way to teach math. Here are some of the math story problems I have used with my second graders. I first give the problem orally, have students retell the story and then have them work on it independently. Once the majority of the class has them solved I have students show their work and explain how they came up with the answer. It is amazing how many ways they come up with to solve the problems. If you let them think for themselves instead of showing them the "right" way to solve a problem they will understand math instead of memorizing it.