Any.do is a brilliant web based task manager & to do list. As its web based it integrates with a wide variety of web based devices and online services.
If you are a busy educator (who isn't?) that struggles to keep on top of all the things you have to do in your day, then you should certainly give Any.do a try.
Alternatives to Any.do
If Any.do isn't for you, you may like to check out some of these alternatives: