Depends how old the kids are and whether the babysitting is day or night... and whether it's sunny or rainy haha! But you could do colouring, make things like fairy wands/crowns or paper boats for boys and fill the bath up and float them, play with bubbles, read books, help them with their homework, do some baking- cookies or a cake!, sew a stuffed toy, play blocks, make blocks! write poems or a little book, be creative and ask them what they want to do! Never just watch TV cause that's boooooring!
how old is the kid ur taking care of? if the kids is like 1-3 yrs olds u can try playing peek-a-boo, make ur own fun learning game...example like an indoor treasure hunt finding stuff like books and stuff like that, u can also have then play with play-doh and use that to spell their name, u can also watch movies, read books, r just play with them using their toys, u can color a coloring book with them and show them how to draw shapes and stuff like that
Play tag, play with Play-doh, color, paint, build forts out of blankets, go on a walk outside (if that's okay with the parents), blow bubbles, draw on the driveway with chalk, ride bikes, pass around a ball, play a board game, ask the kid what he or she wants to do, etc.
its not hard believe me. you might think they will want you to decide but they will be the ones telling you! expeccially if he/she is round the age of 4-8. my first babysit job... the child wanted a boxing match with me!!
Ask their parents what they like doing, and put your own spin on it!
