Underestimate

My daughter (14) preparing for school start tomorrow, in an upset tone:

‘Mama, just imagine: on Day 1 we must return all the tests we did the previous year.
What is beyond me, once they knew they would need those tests, why did they give them back to us? If the school believes I need a whole summer to lose these things they are seriously underestimating me, because I can get it done within as short as 2 days..’