Here's an interesting, and tasty, way to help teach rhythms to your students. I heard this idea at the 2012 Iowa Bandmasters Conference. Sad to say I forget who told it to me, but when I found it in my notes I wanted to share it as it is quite original.
Teaching rhythms is a challenge and making the task a little more fun never hurts. To use this method get a few packages of red and black colored Twizzlers candy ropes. Cut the red ropes into two inch pieces, the black ropes into one inch pieces, and then grab a bag of M&M's as well. Give the student a piece of paper with bar lines on it (spaced appropriately) and have the student create rhythms with the rope pieces. Red ropes for whole notes, black for half notes, and then use the M&M's for quarters.
Once you have all these pieces you can dream up many different ways to have the students use those candy pieces to create rhythms by laying them in sequence on the paper. For an added challenge put staff lines on the paper as well and have them create simple melodies or have them copy songs from their lesson book by placing the ropes on the appropriate line or space.