I can't take credit for this game, but I did want to share it with you since it is such a great idea. I found the original idea at this post from Sun Scholars. (When you're done reading this post, you really need to check out the post at Sun Scholars, it's full of great preschool tray ideas!)
This is a relatively simple game and it takes just a few minutes to prep. I took a scrap piece of card stock, a handful of coins and my Sharpie. I traced the different coins and wrote in how much each was worth. That's all it took! I always present it to Lizzie with the exact coins she will need.
Matching the size can be a little difficult as some coins, such as the penny and nickle, are very similar in size. But, I don't necessarily want Lizzie to just learn the size of the coins; I want her to start associating each coin with how much it's worth. This game has been so effective in helping her learn this concept. She also seems to really enjoy playing it, therefore, it tends to show up in our preschool corner on a regular basis.