My nephew was 7 in February. So was his twin sister. 
They live in the United States, so he and his sister are just finishing 1st grade.
Anyway, one day last week he was playing some game on the family computer. Which is in the main family area. Somehow he found himself on YouTube. He knew he wanted to watch videos of the Power Rangers but he also knew he didn't know how to spell Power or Rangers.
So what did he do? He went to the DVD holder across the room, grabbed one of his Power Ranger DVDs, trotted back over the the computer and copied the title, letter by letter.
Luckily, all he found were Power Ranger videos before my sister noticed what was going on.
Their computer is now locked down tight.
Don't assume your kids are safe just because they can't read or write well yet.
You're welcome.