If you have a Google account, you can add any of the calendars to your smartphone or computer.
Go to https://www.google.com/calendar and sign in. Find "Other Calendars" located on the left of the screen, about half way down. Press on the little down arrow just beside it on the right. In the popup window, enter the cut/paste the url for the category you are interested in.
Pelham Elementary School:
Pelham Memorial School:
Pelham Memorial School Athletics:
Pelham High School:
If you have an iPhone, you have one additional step. Simply go to https://www.google.com/calendar/iphoneselect and select the calendars you wish to see on your iPhone.