Google Keep is one of the lesser known of Google's Apps- and it's a gem! I use Google Keep for...well, everything. It's a great place to store tidbits of information, including weblinks, images, ideas, and pretty much anything else. You can also create reminders, set to remind you at a certain time, or a certain location- similar to Apple's native Reminders app.
What sets Keep apart from other note taking and reminder apps, like Apple's Notes & Reminders is the ability to share with other people. Like everything Google, sharing is naturally built into the software. This is effective in taking the load off of email, as teachers and students can now simply share a note via Keep, and add to that note when needed. The fact that notes are updated in real time allows teachers to add further instructions for a homework assignment to a Keep note shared with a student in the evening if needed. Google Keep is also a wonderful place for groups of students or teachers to share information for an upcoming group project.
As you can see, the options and opportunities are almost endless with this app. One last note, if you are using Google Keep, then you MUST get the Popup For Keep app (see image below). This Chrome extension makes it even easier to record notes on the fly. When you click on the extension button in your browser, a pop up window appears with all of your Google Keep notes in it- without having to go to a separate website!