Try out Quora!
Usability: Quora is extremely easy to navigate through. First off, you need to sign in with either your Google account or Facebook account. After that, you can explore and tag all the subjects you are interested in such as math, science, reading, writing, etc. At first it takes a while to load, but after that everything is responsive and fast.
Support: No tutorial is given however the app has a very basic layout. Once you have signed in, it asks to setup your account, and it tells you how to do that. After that you are free to use the app with no interruptions.
Engaging: This app is very engaging. The reason why is because you have the free will to look up any question about any topic. All you have to do is type it in and there's the answer. You don't have to search through URLs to find the right answer. It is fast and easy.
Export/Sharing: Once you have signed in with either a Facebook or Google account, you can start sharing the answers you've found on the app. You can share them on Google+, Facebook, or email.
Customization: You can't really do a lot of customization on this app. The only thing you can do is customize the tags you are interested in. So once you've open the app, questions and answers of certain topics will already be there. This is there so that you can browse through related questions about topics you are interested in.
Collaboration: There is no collaboration in the app itself, but since you have the ability to share you can collaborate outside of the app.
Import: You can't really import anything, but you do have the ability to answer questions yourself, or ask questions of your own. So you can still add some things to the app.
Overall it is a very useful app. If you ever needed an answer right away, but a teacher wasn't around this is the app for you!