Looking for part-time, day-time babysitter for school vacations

I’m looking for a part-time, day-time babysitter for my kids in the upcoming April school vacation (April 15-19) and for some of the summer. We live in East Cambridge and my kids are 13, 11, and 5, so only the 5 year old really needs babysitting, but the 11 year old likes to play. I’m ideally looking for someone who could watch the kids in the mornings. I’m open to considering a mature and competent high schooler. We live in East Cambridge, between Kendall and Lechmere Ts.