Have you ever been out and about with your child(ren) and noticed that letters you thought they knew, they were unable to recognize on signs, books, and other places? Most of the time when we are teaching our kids letters, they learn to recognize the letters in something close to Times New Roman font. When presented with other forms of the letters, like other fonts, they hit a road block.
This activity is easy to do, and a great way to practice recognition of letters in multiple forms. Just open whatever type of Word program you have (or something of the like) and type a letter about 10 times for capital and 10 times for lower case. Then change the font for 9 of them and ta-da!
I cut them out and had the girls sort them, then glue. Check to make sure they are getting it before they glue, FYI.
Once they get the concept, it's something you can have them do independently. For me, it's something they can do while I work with another sibling with minimal interruptions.