Years ago, I created a spreadsheet to help young children learn their lowercase letters once they had learned their uppercase letters. I created it for my two oldest, and now my youngest is using it. My wife says that it has made that teaching task simple.
The spreadsheet generates seven unique random letters in uppercase on the left, and scrambles them in lowercase on the right. Print a sheet, and the child draws lines to match the letters. Hit the recalc [F9] button, and you have a new sheet. With a little bit of coaching, the child gets the concept in a week or so. The sheets are easy to use, and the limited matching doesn’t overload their ability to remember, particularly because a few letters on each page will be easy.
If it works well for you, let me know.