Here’s a game that will motivate the kids to learn more hymns.
Start by giving them a word of your choice, then they will be given a certain amount of time to think of a hymn with that word in it and sing a part of that hymn
For example, the word is LOVE. The person whose turn it is to sing can sing “Jesus LOVES the little children”, and another can sing “Jesus LOVES me this I know”.
If a person can’t think of a hymn within that given time then they’re out.
Continue with this, switching the required word every once in a while until there is only one person left. That person is the winner.
You can encourage the kids to play by offering a prize to the winner, or having different level of prizes for the top three.