An observation hive is of my favorite things to do with bees. I take a few frames of bees from a hive, put them into an observation hive and take them to a school or group to give a talk about honey bees. I think everyone finds it absolutely fascinating to see bees up close and personal. The fist question most people ask is where is the queen. If possible I mark the queen with a small spot of paint on her back. It's amazing how much easier this makes it to find her.
I once had an one installed in a utility room for a while. The bees came and went through a tube which let outside. It was wonderful! I would ask visitors whether they'd like to see my bees. We would go out, towards the back of the house, they thought we were going outside. Before we got to the back door, in the utility room, I would open the cover of the hive.
It got quite few gasps but I think most people found it very interesting. Seeing bees actually inside their own surroundings is 100 times better than an ant farm. Once people got over the shock they were always fascinated, particularly if we saw the queen.
I recently discovered a new style of observation hive. It's called the Ulster. Basically it's a nucleus with an adapted roof. I made this one for an exhibition so I put a window in the side as well. There's a webcam pointed at the window, you can go here to see the bees live.
If you're handy with a saw you can make a top for an existing nuc. It simply replaces the regular cover. I like to put a queen excluded between the top and the box. This means you can put the frame with the queen in the top viewing potion and she can't escape down into the main box. Since it's basically a nuc, the bees can stay in there for weeks at a time, provided you allow them access to the outdoors of course. Just remember to make sure there's a ¼" bee-space between the components inside to give the bees room to move around. Ventilation is also required when they're enclosed, and if the exit to the outside is down a long tube. I have a screened portion in the floor and some 1" screened holes in the top.
When I put the frame in the viewing compartment I replace it with a frame feeder to help sustain them while they're in the hive.
You can buy one from a beekeeping equipment supplier, or you can quite easily build your own. I think to build your own observation hive with these plans is a very satisfying thing to do.
If you have kids, or know any teachers, you'll very likely to be coerced into giving a talk to the kids. If you get the opportunity, do it you won't regret it. You're the expert and you've tamed these familiar, and yet exotic, insects. You'll be bombarded with amazing questions, even from the youngest children. "Why do bees make honey?", "How do bees make honey?", "What does a drone look like?" Unfortunately if you get any really dumb questions, "Do you ever get stung?", "What happens if the glass breaks?", it will always be from the adults.