Question

which is a thesis statement? researchers have discovered that the tendency for teenagers to stay up late at night and wake up late in the morning is biologically determined. to make school start times more synchronized with teenagers biological clocks, schools should begin classes no earlier than 8:30 a.m. the paragraphs that follow explain why schools should begin no earlier than 8:30 a.m.

Explanation:

A thesis statement presents a main - argument or claim. The first statement is a fact. The second statement, "To make school start times more synchronized with teenagers' biological clocks, schools should begin classes no earlier than 8:30 A.M." is a claim that can be argued and supported with evidence. The third statement is more of a preview of what's to come.

Answer:

To make school start times more synchronized with teenagers' biological clocks, schools should begin classes no earlier than 8:30 A.M.