I know. It sucks.
But not many kids in the modern day remember stroke order for Kanji and remember as much as they did before.
Some things that english classes do for a Japanese lesson is more or less... old. Modern japanese talk isn't like a new language but it's a bit different... Unfortunately some things you have to be a native to know. I know a lot of people who pick up Japanese to understand what their favourite anime is saying. I never say it to them, but the chances of them understanding it under the teachings of a normal class... is rather minimal. Because things are just taught too formally.
Anyway back to the topic, the Kanji stuff is basically like... like Homophones. They sound exactly the same but the meaning is different! So like you said there is no other way but to memorise. Just like how we learn words. We learn them by listening to other people. Like the words 'where' and 'wear' they sound the same but there is no trick to knowing the difference. We just learn and remember.
That's why I just said that some may be hard to learn unless you have been speaking that language for a while. As demotivating as it is, it's those who don't give up that achieve highly.