Thanks for the advise Clive. I shall consider that. I had some more ideas about having some crosswords that are half completed for pairs of students. The students then have to explain the word for the their partner but they cannot show their crossword to each other. Just an idea and should eat up loads of time. Found a website that can help you create crosswords (probably good for kids):
Free Crossword Puzzle Maker
Btw, how's your kid nowadays? My son is 3 and a half now. He's going to kindergarten everyday and he enjoys it. He has started to mix English with Korean. Sorry, it should be a separate topic.