It's actually kind of a difficult question. I'm assuming your teacher wants you to write about helots, and just kind of took it for granted that helots and slaves are the same thing. This is not quite right.

The helots were the original local population of Lakonia and Messene, the areas conquered and ruled by the Spartans. These people were stripped of all freedoms and forced to work the land for their Spartan overlords.

However, they certainly were not chattel slaves. They could not be bought or sold. They were tied to the land rather than to individual Spartans. They were made to fight for the Spartan cause in war, and in the Classical period many gained their freedom this way. They formed a cohesive community that retained its old cultural identity, had leaders, some level of wealth stratification, etc.

Scholars disagree on whether they count as slaves or not. Most seem to prefer the term "serfs".

I think you should probably go to your teacher and ask him/her to clarify whether they mean the helots or slaves proper.