"Pre-schoolers love to play."
In this sentence, "pre-" is the prefix, and "schoolers" is the word it is attached to. The prefix "pre-" means "before" or "in advance," so "pre-schoolers" means "children who are before school age."
Here are a few more examples:
* "The post-game interview was exciting."
* "The under-water world is fascinating."
* "She was the only one who could decipher the code."
Let me know if you'd like to see more examples or have any other questions!