Babysitting entertainment ideas????

okay so i am babysitting these 3 girls down the street i am 13. one is in 2nd grade and she is very hyper and like needs attention i guess you could put it that way. And then the other 2 girls are in 4th grade and one is very mature and likes to do about everything, and likes math and english and the other one is also very mature and likes crazy contraptions and science stuff and anything like that. I went over once and now they want me 2 come over again with toys and stuff 2 entertain them. What can i bring that can entertain them????? budget is like idk under $25 or $50 which is still alot. HELP PLZ i need to keep my buisness up!