Good Exercises For Legs ? Running?

Im a 15 year old girl and i try my best to work my legs i , go for a jog 3 times a week and do some press ups , push ups but i dont think they work the legs ,the only exercise i know that makes your legs stronger is Squats and i do 10 Squats 3 times a week two .my legs are strong i think but i want them to be stronger. iv got sports day tomorrow at school and im doing 800m and im not that confident i will win .last year i came 3rd so i want to improve that to 1st .please help thanks u :)