All time-management tools

Google Calendar

With this online calendar you can keep track of appointments, classes, assignment due dates--practically anything time sensitive--and set reminders to alert you to upcoming deadlines. You can share calendars with anyone else who uses Google Calendar.

Google Keep

This Google app lets you create virtual “sticky notes” with to-do lists--with reminders--that you can access from any Internet-connected computer or mobile device and share with others. Versions for all computers and mobile devices are available.

What does it cost? Free! Included in Google G Suite (go to http://keep.google.com or search for it in Google Drive), and available on the Apple App Store, Chrome Web Store, Google Play (Android). 

Remember the Milk

This online service (and app) is essentially a superpowered to-do list that sends you reminders to keep you on track. You can share these lists with two people. 

MyHomework

With this online service (and app) you can keep track of your class schedule, homework, and tests/quizzes--and set reminder alerts. You can access your information across all your devices.

MyStudyLife

This free web tool does everything that myHomework does--just in a different interface. It helps keep you on track with your class schedule, homework, and tests/quizzes, across all your devices.

WEBSITE: University of Minnesota Assignment Calculator

There are plenty of assignment calculators out there, but it seems like most of them are based on the one developed by the University of Minnesota.