clock kits

I've seen kits offered on the internet, and I would supervise the lad so he knew what he was doing, but I mentioned the clock reaction to him when he was pondering a science project for this Spring. I don't think the chemicals used are dangerous enough to warrant more than eye protection and gloves, but is it too much for a 9 year old, or will his classmates be oohed and aahed? Thanks.

There should be an age recommendation on the box. Check it out. Even if it is recommended for a slightly older child, he could still do it with adult supervision. An alternative may be one of those potato clock kits I have seen in stores.