Then it would be correct to say that the children have been exposed to the materials, as I said before.
All of us have been forced to read sloppy writing for so long that we "fill in the blanks" when something doesn't make sense, which is what you did. Most people do it automatically, although I bet there was a split-second in which your brain said, "Huh?" and then figured it out.
I've seen it happen to my fiance, and he doesn't realize he's doing the writer's (or speaker's) work until I point out that he had to make some leaps of logic to get the point.
It is always the communicator's job to get his point across. If we have to stop and think, "Now did he mean what he said, or did he mean something different?", that communication has failed.
If I make you think about why I said what I said, instead of what I said, my communication failed.
I adore your grammar lessons........they keep me on my toes.