Why do they do this? There is so many things wrong with this!?

Why do they teach us the wrong terminology? Like using jelious instead of envious? Envy is wanting something, jealousy is having something and not wanting to lose it. And why do they still call it the Guilded age? They say guilded means covered in gold, then they say how everyone was living in terrible conditions and only a few people are rich, so why is it still called the Guilded age? And they say we get energy from the sun's heat in elementary school, then in middle school they say we actually get heat from light, why not just tell us all this at first? Finally, when you smoke weed, why is called getting high, when you are usually down and mellow?