Classroom pet recommendations?

[Tek]

A parent donated a small fish tank; the students really want a class pet and I think it could be a positive addition to our classroom.

What would be better to get: 2 goldfish or 1 beta (fighting) fish?

I am also thinking big here and thinking of a guinea pig... but maybe not such a good pet for 6 year olds?

The fish would be the easiest to maintain, but I wish it could be something they could actually hold and pet. But maybe I should just keep it simple. Thoughts? Experiences on 1st grade classroom pets and which animals work well and which ones do not?

[pwhatley]

I think a beta fish would be perfect - they are super low care, and won't eat themselves to death like goldfish. We actually had one at home for 4 years!

I've actually been considering an ant farm - I think it would be fascinating!