i like topgrade because it's a online platform for those student which can't go outside. 1st thing i like about topgrade app you can take few days trial classes and 2nd thing is you can give tests and check how much you are peppered for your exams.when i take 1 day trial class i thing app is not good it's just waste of time, but when I take some more days trial classes then I start understanding the lectures and i love topgrade I found it by search in chrome I wish I Was found it early when I was in 1st and 2nd year but it's okay because i can now study for my MDCAT exams in topgrade.