Have you read Number Talks: Helping Children Build Mental Math and Computation Strategies, Grades K-5 by Sherry Parrish? It is a great read if you are looking to build your students math abilities.
I was lucky enough to receive on through my county and I am so happy I did. It has changed some of my thinking about math instruction :) If you can get the book, I suggest you do...but if not I have a few other resources I think you should check out.
First, check out Cathy Young's article Implementing Number Talks Helpful Hints and Number Talks: What is it?
Then check out these sites that have lessons to watch!! Inside Mathematics: Number Talks & Math Solutions: Video Clips
In my classroom, we start everyday with a Number Talk. I have a problem waiting for them on the board. They read the problem and mentally try to solve it. When they have a sum they hold their hand against their heart and put a finger up. Then they try to solve it a different way. For each way they use to solve the problem a finger goes up. I call for answers and take them all right or wrong. Then the students are given the opportunity to share how they solved the problem. They talk us through it while I document it on the board. Then we move on to another students way.
The goal is to have students use Mental Math. We know in first grade that will happen but first we need major scaffolding. So you can also tie it to journaling. I have a couple scenarios (Number Talks) for your class to try out. At first they will look at you like your crazy but once they understand the concept they will get so excited for the daily Number Talk!
This was a short and sweet post but I hope you get down and dirty and follow the links to learn more about Number Talks!!