Afternoon babysitter needed

We need an afternoon babysitter for our two girls, ages 8 and 11, in Menlo Park, close to campus. Job would involve some driving to local sports and activities, keeping them company, helping with snacks and homework, playing, etc. We can use 3-5 afternoons from about 3:00-6:00. Days somewhat flexible. Possibilities for weekend evening sitting if you are interested. Thanks! Lisa