My girls and I do a lot of singing. It helps them build a rich vocabulary and promotes imagination too! Young kids all love to sing and you will be very surprised to see how quickly they learn a new song even if it is in a language they don't speak. It is a great way to expose your child to a second language which they will be learning without even realising! It is a great exercise for native speakers too, since it promotes good use of grammar, syntax and word association.
Here is a song called Τα κουλουράκια. Use the printable to laminate it or print it on a card paper and hold it for your child to look at while you are both doing the singing. You can also watch the video of Maya singing the song. She is a bit distracted but you can still get an idea of how to sing this song with your kids. It is a very cute song and you can do some lovely cookie baking to accompany your singing too!