This is a fun review activity that I can't take credit for. It works best for Senior Primary because it involves reading.
Pick some key words from a song and print them in a large font. Choose a child to come to the front and face the Primary. Put a hat on the child, then, without letting them see, tape a word to the front of the hat. Make sure all of the children can see the word, but tell them not to say it out loud. Then sing the song, but when you get to that word no one sings it. At the end of the song, the child guesses the word. If they get it right, another child comes up and you start again with a new word. If they miss it, sing the song (or part of the song) again, and give them clues to help them out.
If they need an extra challenge, put two words on the hat.
Here are the words I used for "As a Child of God."