Digraphs are two letters that make a single sound. A few examples are ch, th, and sh. Digraphs are an important part of phonics instruction, but you can also make them fun to learn.
If you have a beginning reader who is working on digraphs, you'll want to head over to This Reading Mama to print off her Digraph sorting picture cards which she generously provides as a free printable.
I also saw a great printable for a digraph game from The Measured Mom (via 123 Homeschool 4 Me) that we're going to try.