Corrected sentences:
Hares have long, strong back legs for jumping and running.
Their front legs are shorter and help them turn, stop, or thump.
- Why we changed the first sentence: Saying "big, long" is a bit clumsy. For a child it sounds better to say "long, strong" or just "long."
- Why we changed the second sentence: We used "shorter" to show a comparison with the back legs. We also used "thump" instead of "drum" because animals usually "thump" their feet on the ground.
- A short note about meaning: If you meant the front legs help the hare make noise with the ground, that is unusual—hares usually thump with their back legs. If you meant the front legs help the hare touch or tap, you could say "tap" instead of "thump."