To get you started, I can say that they generally seem legit and could definitely be from the Ohio Valley (but since point styles tend to cover rather large multi-state areas, getting more specific than that is out of my league). I do question the large piece, which seems more like a stone that broke off in vaguely "tool"-like shape rather than something someone actually worked. The first two images of it do make it appear as though it has an edge on one side (in which case it might be a scraper), but I'm not seeing the striking pattern that I'd expect if someone actually shaped it that way. Of course, it might just be a trick of the lighting. Also the second biggest piece is a bit confusing as well. Whatever it is, it's definitely not a projectile point either.

As for the points, they're not arrowheads. They mostly appear to be Archaic dart-points, from anywhere between 10,000 to 3,000 years ago. This is especially true of the ones with bifurcated or fishtail looking bases. One notable exception is the one in the center of this image with a stemmed base. This style is more common in the Woodland period (3,000 to 1,000 years ago), particularly during the first millennium of that era where the style is closely associated with the Adena. The darts that these projectile points were used with were heftier weapons than arrows and were thrown with use of an atlatl, or spear-thrower. The atlatl was the dominant weapon through the Archaic and most of the Woodland periods, until the bow started to become common toward the end of the Woodland. To give you a quick glimpse into the time periods in which these projectile points were used, you might be interested in this series of posts I made last year, especially the second and third in the chain.

Hey, very cool photos - thanks for sharing.

What /u/Reedstilt has told you rings true with me as well, but I thought I'd comment to share this anecdote, which I hope I can have some leeway on (sorry mods!) because it's also advice.

My family and I recently returned some projectile points collected by my grandmother in the mid-century to the local First Nation - they brought in an archaeologist who works at the big research museum nearby, and she was able to tell us a lot about them. If there's a big museum or university near you, it might be worth asking to see if there is anyone who could help you out with more info as well.

Another cool idea, depending on the age of your students, would be to get them to help you research it, as a big class project.

Anyway, good luck with this!

Wither or not your arrow heads are "authentic" I have no clue, but you could show the kids how these arrow heads are made by hand. And who knows, maybe your willing to allow the kids to try to make their own under supervision. Get their prehistoric tool making juices flowing!