Trek 800 Sport

Today I picked up this Trek 800 Sport at a thrift store. I’m thinking that with a little petroleum grease, elbow grease, some adjustments and not much more money, I can get it rolling again (looks better in the photo than it is). My intent is to introduce the Grand-kids to a multi-speed bike. Just looking at it I think all 3 of them could fit on it and ride it. It has 26 inch wheels but just a 13″ frame. I don’t know much about the bike. I’m guessing a entry level MTB from the early 2000s possibly 2001.