Here's a stance workout for the primary level student at our school....

A Beginner's Exercise (stance training)
1) Horse stance held properly for 1 minute minimum.
2) Switch to a reverse Bow & Arrow stance for 1 minute (both sides).
3) Back to your original Horse stance for 1 minute.
4) Shift into a Cat Stance for 1 minute. (both sides).
5) Step out into a back stance for 1 minute (both sides).
6) End in another Horse stance for 1 minute.