(placed in spoiler to avoid polluting the comment thread)
But if we are going to nitpick them on a missing apostrophe, I would like to form a mob and attack a few of my middle and HS english teachers.
Also, lets kill whoever allowed this crap to begin with. Your and you're. There, they're, and their. Live(don't die) and live(recording).
Seriously though, school must have been hell for you. I swear they didn't even try to do a spellcheck on those textbooks, much less check its grammar.
Math was even worse. Not only was the grammar and spelling wrong, but even the easily computable answers were often incorrect. And none of the math teachers I met knew proper grammar for their own subject. "And you times it by.... plus it by... minus it by...". Every day by both the teachers and students. They only memorized the shortest word for the operation and then used it in every sentence, no matter how stupid it sounds. What more, most of the math teacher didn't actually know math. They relied on a calculator for any operation with more than 3 digits. And the ones who told me it was impossible to do simple math (like calculating roots) without a calculator can burn in hell.
... I might have slight anger issues...