Please watch closely and if you see the children are frustrated, do not push them. Know that this will be covered in Kindergarten. You helping them to start learning now is a good idea, but do not push them. If they are not ready stop. Remember that each child is different and some may get it and some may not.
Children can learn so much from songs.
Of course they do not help with visual skills. So you have to make the songs more visual. Use a felt board to animate the number songs. To make the songs more visual cut a shape from either paper and add felt to the back or from felt. You can even use a shape for the time of the year or you can a standard shape.