Using Zap Calendar is a popular choice for schools.  Did you know Zap Calendar was initially developed for a school?  Here are a few suggestions for Zap Calendar that you may wish to use to get your web site ready for back to school:

Set the yearly view in the calendar browser to display the school year instead of calendar year.  So instead of showing the yearly calendar from January to December, show the school year calendar from July to June (from the view editor, select "Yearly" tab to change).

Parents can receive weekly e-mails of upcoming events by setting up an e-mail subscription service.  This can be set up to send out the e-mails automatically and is explained in the tutorial, Receiving Upcoming Events Automatically by E-Mail

Consider creating multiple calendars for divisions like upper and lower school, or perhaps school and sports.  Each calendar can have its own categories and even share categories. For example, an upper and lower school may share a "school holiday" category.