As I mentioned on my site, I never place rats to elementary shool classrooms. Such an environment is stressful and unhealthy and rats suffer poor mental/emotional health there. Also, children can be allergic to rats and it is impossible to minimize allergens in most classrooms.
However, rats are often kept in high school and college classrooms as "pets" rather than research animals. And whether or not this is a GOOD situation for the rat, I have decided to write some guidelines/tips for teachers who want to keep rats in such a situation. (Personally, I think mammals in classrooms do not generally do well, but if they are going to be kept there, we should do what we can to keep them happy.)
Other needs outlined on the care page are all the more essential for classroom pets. With a couple additionl concerns:
Companionship: It is VITAL to provide rats a companion. A pair or trio of sisters or brothers is best. Rats draw courage from each other, so a single rat is NEVER an option for a classroom setting.
Housing: I think a large aquarium is a much better option than a wire cage in a classroom setting. It minimizes contact between the students and the animals which lowers the problems with allergies, the spread of disease, and the potential for "teasing" the rats, giving them unhealthy treats when you aren't watching, or getting their fingers nipped. It also reduces the flow of sounds and scents into the cage, which can be a sensory overload and make rats nervous. (Also make sure the lid is secure! An escaped rat in a school can cause a lot of ruckus and is really an AWFUL experience for the rat!)
Litter: Make sure you are using the best litter possible, if for no other reason than to reduce students' allergies. Paper-based cat litter usually works best. Also, your classroom rats will be an example for those who are interested, so set a GOOD example.
Toys: It is VITAL to provide an opaque box for the rats to hide in when they want relief from the light and the watching eyes. Other toys are a good idea too. Rats love bits of paper and cardboard especially.
Care: With high schoolers and college students, "class pets" are not there to teach students how to care for animals, but are rather there to observe behavior and learn about other species. Care should NOT be a classroom task, but rather the task of the teacher or an individual student or a pair of students or small group. If this is a student's "chore," you--the teacher--need to make sure the rats' food bowl and water bottle are ALWAYS full and that the cage stays clean, especially on days the student is absent. This is not a task that sould be expected of an average substitute.
Rats need darkness. In fact they need at least eight hours of complete darkness every day to stay healthy. Being in front of a classroom and/or under lights all day is stressful and unhealthy. It is better to keep rats at the back of the room, under a desk or in a quiet lab most of the time, perhaps bringing them out to show the students on occassion. (Another reason to do this is that the rats will be a distraction to the students if left out in front of them all the time.)
If the school turns off the heat or air conditioning at night, someone (the teacher or primary care-giver) needs to take the rats home. If the school temperature is relatively stable, the rats can be left over weekends (not extended weekends, though) if given extra food and water. On holidays and summer, they need to go home with a primary caregiver.
Bonding, Mental Health, and the End of the Year
Rats need stability of one person they can bond to. A good way to get new rats comfortable and calm is to have this person, who can be their "primary caregiver" (the teacher or an interested student), take the rats home for a week or two before they become "classroom pets." This will give the rats a chance to bond and learn to trust people. The rats will come to rely on this person's attention everyday.
If this bonded person is the teacher, there is no problem. The rats will be able to see and interact with the teacher everyday for their whole lives. However, if it is a STUDENT, a problem arises when the term is over. The rats have gotten attached to this person (even if you didn't mean them to; they will bond to whoever feeds them and spends the most time with them), and the student will be moving on. Rats are not animals that can mentally handle this separation (some other animals do NOT bind tightly like rats do), so if their caregiver is a student, arrangements should be made for these rats to join the student's family and leave the classroom life. (Ideally such a student would be doing an internship or something that would keep them frequenting the class for at least a year...)
NEVER breed rats in the classroom nor house (unneutered) males with (unspayed) females. Rodents are very sensitive animals and the stress of classroom life can cause aborted pregnancies, cannibalism, or any other horrible thing that is neither natural nor pleasant. If your goal is for students to experience an animal's breeding and life cycle, rodents are NOT a good choice. Instead, try some species of frogs (African Clawed Frogs make pretty good class pets) or fish, which are not as stressed by classroom life. (And are not as hard to keep or find homes for the additional critters from the breeding.)