Letter Confusion - Any Ideas?

I am using this book to teach Kyle to read and it is going great. He is doing so well, but when he is sounding out the words he gets mixed up between lowercase b/d and h/n. It is frustrating for him and while I know he will eventually learn to differentiate, I wish there was a way to make the process quicker for him.

I made these little cards with the lowercase b, d, h, and n and inside the lowercase I wrote the uppercase of that letter (he has no problem with the uppercase). We cover the uppercase with a magnet and he says what letter he thinks it is, then uncovers it to check himself. Does anyone have any other ideas for how I can help him learn to differentiate these letters? A rhyme maybe? Or a different way of thinking about it?


You can order cards to go along with the book or you can make your own. I had a ton of index cards so I decided to make our own.