

This is off topic and I hope that you take it in the spirit offered. I can never decide if it’s rude or helpful but the intent is to be helpful.
Teach is one of a handful of words in English that doesn’t follow the normal rules for it’s past tense form. The past tense for teach is taught. I honestly can’t tell you how to identify which words use a different form for their past tense. I think it’s just something that you learn through experience.
https://www.esl-lounge.com/reference/grammar-reference-most-common-irregular-verb-list.php
There are already lawsuits filed for refunds of tariff payments. Of course the money will go to the companies that made the payments. All of us who actually paid them by paying more for basically every consumer good are out of luck.