This was a student idea. I wanted her to make a story problem that we could share with another class, in order to analyze their strategies and make our own more efficient. It is a very difficult problem, but there are many ways that you can get to the answer. I did this with a grade 3 girl, who is quite advanced in her mathematical reasoning (my only student!), but I think it would be appropriate for any grade from 3-6.
It was also a good way to integrate some language and technology skills into our math class. She came up with the problem, wrote the script, planned the shooting, and helped me to edit the movie in iMovie. I worked the camera and showed her how to navigate through the editing options.
Give it a try and send along your students responses so we can analyze them. Good luck, it is quite challenging!