Fun things to do with 11 and 7 year olds?

I'm babysitting an 11 year old and a 7 year old and I have no idea what to do for fun. I'm used to babysitting much younger kids.. I took them on a walk and played with chalk and hide and seek but they got bored really fast and then we couldn't think of anything else to do.. I have two more days with them. Help!