I came up with the following practice cards. On one side a two digit number is written and on the other side is a picture of beads. The child uses these cards with the tens bead box. The child chooses a card, makes the quantity with the beads and then turns over the card to check if she has the right answer.
Sorry about the second picture [it's not clear], Annabel was playing with the beads and I had to take the picture quickly before she messed up the materials.
I have added the file to my box.net account, feel free to download it and please do leave a comment if you do. I'd love to know how you used the material and whether it worked for you or not. To make it up, print all six pages, then cut out all cards and glue the corresponding cards together and make sure u stick the correct pieces together. Then laminate.