What happens if they don't have a UVB bulb.?
Depends on diet and temperatures.
I am unfamiliar with flukers turtle food. Bearded dragons are very adaptable and forgiving when it comes to diet- depending on formulation of the turtle food, it may not be as bad as it might sound at first glance. If it has a decent formulation for omnivorous turtles, it is possibly not too bad for bearded dragons either. Especially if rounded out with fresh veggies and insects. But as I do not have experience with or knowledge of the food here is my advice-
You can help inexpensively by getting the lizard a bottle of rep-cal bearded dragon food and ensure it has plenty of heat (100-110 basking spot)- make sure it can escape the heat on the cool part of the enclosure down to at least the mid 80s.
These two ingredients (the pellets and the high basking temp) together will prevent MBD.
I know this from experience- I've been breeding since 1994 and have experimented with large groups using different methods of feeding and husbandry. Rep-cal pellets do not require UVB for the animal to get enough vit d3 to remain healthy and have good bones. BUT- I suspect strongly that warm enough basking spots are important for proper absorption of dietary D3. I would not count on the pellets without the basking temps I am recommending. You can tell if temps are correct because the dragon will be light or bright colored most of the day and only bask intermittently, often basking a little off to the side rather than the warmest part, except when first warming in the morning or last warming in the evening or after eating or drinking. Constant basking means he can't warm enough.
It is still better to ensure the animal has a UVB lamp as well, and it is best to offer a varied diet of fresh leafy vegetables as well as supplement dusted insects alongside the pellets. The insects can be fed occasionally to adults which can be mainly vegetarian or mainly pellet and/or vegetable eaters.
A bottle of rep-cal pellets can be purchased for $10 at petsmart. A box of 4 100 watt light bulbs can be purchased for $1 at walmart.
$11 would help.
For another $25 you could add the UVB lamp and fixture.
$6 you could add rep-cal with d3.
Maybe take up a collection from your fellow students and start with the pellets and light bulbs, move on to the UVB lamp, add a mealworm or dubia farm to the classroom and rep-cal with d3, and bring in fresh veggies (spring summer and fall can be free- clover, dandylion greens and flowers, plantain, etc from an untreated lawn are great).
And volunteer and get volunteers to rotate cleaning the water dish and tank daily.
A dirty tank has no place in a classroom anyway- not to mention the poor lizard.
Probably best results will be had if you or some outgoing classmate voices concern for the lizard in front of the class and volunteers to help correct the situation at that time. It will be hard for the teacher to not accept in that situation.