Alphabet discovery bottles are an excellent for letter recognition and review. You will need an empty plastic bottle (make sure it is dry and clean) ... white rice ... and colored alphabet beads (I purchased mine a michael's craft store). I put the rice and the beads in and because my bottle was larger than a normal water bottle I put two beads for each letter in the bottle. I also made letter cards that the children can mark off each letter as they find them. You can find the patterns and a video of this activity here.