After some tortuous sessions of trying to learn them by heart with me, DS is now racing ahead by listening to this CD
He loves it - it has less soppy voices and tunes than some of the others available, he thinks it's funny, and because each one has a differnet voice and style, it is easy to instil them in his memory. It's also quite well structured, with 'karaoke' versions after each song t sing the numbers themselves.
It's driving me whacky - but it is working!