a 8 gallon water change 3 times a week shouldn't take you more than 1 hour in total =) as for the rest of the time, you can study! LOL!
btw... you're grade 8 only? nice tank, I did WAY worst at your age..
My ex gf once tried to help me change water for my tank, in chinese, tropical fish direct translation is (hot water fish).. so i took a nap.. and when I woke up, they were all cooked, and i asked "WTF, why are you putting boiling water in my tank?" she replied "but they're hot water fish, maybe they're just resting".... sigh!!! i wuz grade 9.. LOL! I will not trust a woman again!