Question

How can i make my thesis statement better?

"Within the four years of High School, freshman year is the most important school year for a lot of students."

Answer 1

Your thesis statement should have your two or three reasons why freshman year is the most important year. For example, “Within the four years of High School, freshman year is the most important school year for a lot of students because [reason 1], and [reason 2].

Answer 2

I would suggest switching "a lot" with "many". The word "many" gives a bit more with the professional flair. This is just my suggestion. It helps with the overall attitude, but it's fine if you want to keep it how it is. :)