I have been watching the news but I didn't understand why Russia invaded Ukraine to begin with, we never studied anything like this at school and, with respect, I'm a bit younger than you and Richie, so although I'm following the news I had no idea of the background.Didn't you have a moment to watch the news? Yes, I saw that scene with the tank.
Ritchie has already explained what's behind it.
Putin wants to go down in history as the hero who has re-established the Soviet empire again. He has been traumatised by its collapse in the early 90s.
One of the major reasons for his move now were the demonstrations in Belarus some time ago when Lukashenko was seen running around with a Kalashnikov which made it clear to Putin one more time that democratic developments at his doorstep would be the biggest threat to his autocratic regime. He wants to prevent the same from happening in Ukraine by installing a pro-Russian regime as a buffer zone to NATO countries in addition to Belarus with his buddy Lukashenko.
What is appalling is the brainwashing of the Russians who often don't even know what Putin is doing in Ukraine.