To help my quest for geographical knowledge, I searched for geography apps, and the best one I found was Maps of Our World. (I own an iPhone, so I don’t know if it’s also available for androids.)
In the free version, you can view a map of every continent, plus a world map. Each map will show you locations of every country or major cities. There are also physical maps you can unlock to show mountains, rivers, and other natural features.
When you think you’ve learned all the countries, you can take a quiz of all the countries, capitals, or major cities! (For my purposes, I’m just looking at countries.) And you can repeat the quiz until you know all the countries! It’s a great way to review, and I use it often! The ads are a little annoying, but they have to make money somehow, and the app is certainly worth it.
I highly recommend it for your geography review. (PS: I’m not affiliated with the app or company in any way – I just liked it.)