An important pre-operational math skill is classifying (aka sorting). Children need to be able to compare items and determine common characteristics to build up to more complex math concepts. I thought that this might be a good way to help Erik cement the difference between lower-case and upper-case A, so we gave it a shot.
I took all the letter a items I had collected for our sensory bin and put them in a pile on the table. Then I wrote "A" on one paper and "a" on another.
Despite everything I've read that says little kids come with a love of sorting things, Erik has never been real excited by the idea. He stuck with this for a few minutes, but got bored quickly. That's okay though, the goal wasn't really to get him to sort every single letter a, but to get him engaged with and exposed to the letter. He picked up and manipulated lots of A's, each with it's own size, texture, weight, etc. He was comparing them to each other and really thinking about which was which.