Luke Graham found Brainly:

• Significantly builds student knowledge“Brainly is a huge learning community with hundreds of questions answered each day. The cool thing about Brainly is that all answers are stored on the site, and can easily be searched for by question. Sometimes, I just search up random questions from different subjects to gain knowledge.”
• Significantly increases student collaboration“This is one of the main features of Brainly. Brainly is not just a QA site, it's a community. A community where students, parents, and teachers share their knowledge with each other. I think this sentence provided by them really sums it up: "Nobody knows everything, but everybody knows something".”
• Significantly reduces teacher workload“Before joining Brainly, I would have complex explanations that weren't really to the point. Now, within minutes of asking a question, I can get a simple yet thorough explanation, which is much easier for teachers to review than a jumbled explanation.”