Very educational site, it has events every day that involve educational value and it varies from
--Letter Squash ("In Letter Squash, each round we display a topic, and then a string of letters, which is an in-order smash-up of all the letters in 3 words relating to that topic. The first user to say the three words out loud wins the round."),
--Scion Solutions Quiz (Where it teaches about loans, payments, etc.),
And even more. It has quite a lot of science in it, also. The more you explore this site, the more educational values that you find. And they're even put into fun games! Sometimes, some of these games will give out "clams", which is like the currency/money on Whyville.
Though there is a lot of educational value, there are chatrooms, "Y-Mail", and forums in Whyville that are not constantly monitored. There are filters, but some kids make some creative spellings to get around the filters and use inappropriate language. Also, kids can dress up their avatar to look sexual and make sexual gestures in chat. And, along with this, I know many people who have connected on other social networking sites and have shared personal information, despite it being against Whyville's rules.
I'd suggest it's for the more mature child, and I would monitor it often if I were a parent.