By collaborating together on a project for students, teachers and media coordinators can reduce class size by then splitting the class to teach smaller groups. I recently worked with a third grade teacher to reinforce division by having the students write a real life story problem that would use division, then write out how to solve it and create a powerpoint to represent it as well.
We started with a whole class introduction where I showed an example and we talked about when we might use division. The kids then started writing the story problems and solutions while the teacher and I could both circulate to assist them. We found that this was helpful because the kids were pretty good at writing out the story but writing out and explaining the solution really made them have to stop and think about how division works and how they work problems out.
The next two days I took half the class and led them through their powerpoint while the teacher kept the other half to reteach or accelerate, then we switched the second day. In creating the powerpoint, we made a two slide powerpoint that the kids typed the story problem on the first page, the answer on the second, and used clip art to also represent the problem.
The fourth day we used to present the powerpoints. To keep the students not presenting engaged, we had each student try to solve each problem before showing the solution slide on each powerpoint. 
The kids LOVED this project and were already asking when we could do it again. The only thing I would change would be instead of just using scratch paper to solve the problems, I would have them label each problem with the student presenting’s name so we could go back and see which ones they solved correctly and which ones they had trouble with. All the students were engaged from beginning to end, high students and struggling students alike. Being able to choose a situation they were interested in helped as well. We saw topics ranging from sports to food to the mall to gardens. It helped reinforce division for them, but also gave the classroom teacher some time to work with a smaller group of students in the classroom, so it is really a two birds with one stone. Here are some pictures from their presentations, I hope you can read some of their problems and solutions. I mostly put photos of the solutions because I wanted to show the different ways the kids explained how to solve the problems.
