Wunderlist is a to do list that allows you to list all the tasks you have to do. You can even tick them off when you have completed them. Wunderlist also works really well with Google. They even allow you to sign in with your school Google account. There is also a mobile app you can download to your phone. Click the title link for more information.
You also have access to a Google Calendar with your school gmail account. You can save assessments from the assessment calendar here as well as add your own tasks. Google even allows you to share your calendar with other people. Google calendar is also able to be synced with your smart phone so you get notifications of when tasks are due. Click the title link for more information.