Where are the proofreaders?
Here's an error I came across this morning in a book called Reading Comprehension - Grade 8:
Without moving a muscle, the ball plopped right into Dad's box of popcorn.
On a curriculum website, one word shows up on most pages: explanitory.
Then in a children's historical novel: It's tangy sweetness tasted wonderful.
These are mistakes that show up in writing intended for education!