Google Calendar allows for greater connections to my students and parents of my students. It is also a great tool that allows me to chronicle what happens in my class on a day to day basis. I have a separate Google calendar set up for each of my courses (Physics, Chemistry, Earth Science, and Astronomy). On each calendar I place a description of what we will be covering and the activities we will be completing in class. I also have the ability to attach documents, links or other information for quick access for my student. I typically attach this information to a different section or my classroom website, but the option is there and can be very useful.
I invite all of my parents to subscribe to my Google Calendars which allows them to view what we are doing in class at any time. My calendars are also available to any that may have interest; administrators, other teachers, etc. Now that all of my students have their iPads (as of last week) I am going to help them to subscribe to my calendars. This gives them direct access on the iPads or anywhe they might access their Google Calendar (phone, laptop, home, etc).
Google calendar is just one more way that Google Apps for Education helps my students and I to be more connected and be able to spend our precious time focused on learning.