I think a better question would be: As an informed adult, what species do you think would be best suited to hands-on classroom activities for elementary schools?
What the kids want to see and what they should be handling are two separate things!
My votes were corns, balls, and blue-tongued skink. Corns that are used to frequent handling are not 'fast' and do very well with kids. Balls are great, too, but since they tend not to hang on to people much they are more likely to get dropped if you're not careful. Few lizards tolerate handling by classes full of kids, partly due to the fact that they can hear all of the noise, which can get them stressed to begin with. We don't let kids hold our BTS, but we do let them touch it (ditto for our bearded).
Burms and boa constrictors are very popular, and we do use them quite a bit. However, I wouldn't rank them above the first 3, and given the increase in severity of a potential incident, I wouldn't recommend them to anyone. Not much of a liability concern with a corn snake, but I would definitely take reverendsterlin's suggestion about insurance with burmese pythons. Incidentally, we do carry $1M liability, which we pay through the nose for.
Pixie frogs (and other frogs) could be useful in a display capacity, but I wouldn't generally let kids hold any amphibian in a group setting.
I'm not a tarantula expert, but I believe there could be some concern about kids holding them and then getting some of the irritant hairs in their eyes. I understand this can be quite painful. Again, I'd go with display only for them, or have only the presenter handle them.
Some other things we use: Everglades rats- generally great, honduran milk (and other tricolours)- tend to be 'fast' but our honduran is fabulous, bull snakes, eastern indigo, brazilian rainbow boa, sand boas, rosy boas, western hognose.
However, the mainstays of our programs would be garters, n. waters, e. milks, black rats, e. foxes, e. hognose, browns, and native turtles. I think the most important things to let kids see and feel are the species which they may encounter outdoors here in our province. Of course, then you're into dealing with getting authorization from the MNR, etc. which is hardly worthwhile unless you are really serious about what you are doing (read- fulltime programs). Garters and browns do not require any authorizations, however, and can be very useful in programs as they occur throughout most of Ontario.
These opinions are based upon: 9 years of doing herp programs on a professional (for money) basis (fulltime for Jenny since '96 and for me since ~'2000), >200 programs annually at this point.