saves the contestant. It never fails. Usually at the $2000 or $5000 level. The (idiot) contestant is going home unless the 10 yr. old saves him/her. And guess what? Always saved. So scripted. So predictable.
What does happen is the kids get study material specifically for the show, and are among the smarter 5th grader's you will find so are more likely than not to get the answer correct to begin with.
The timing of the save is based on the fact that people will TEND to use the PEEK first and the COPY second and statistically it happens about half way through once the easier questions are done. It is slightly contrived but not as contrived as you think, especially as others have said, sometimes people do go home on question 1 or 2, and sometimes the kids do get the questions wrong.