Take the tank home or return the fish to the pet shop. Just don't leave it to starve or die from neglect in a classroom where water changes could be an even greater chore than feeding.

Water changes are no problem, it's the number of times a week I would need to go to the school. I would certainly not leave animals to starve; that's why I'm asking the question here.

I always posted which fish were available for adoption a couple of week before school was out. That gave me time to find out if they would be compatible with fish the adoptive family already had. It also gave time for a family to set up a new aquarium if they chose to.
Most times the fish came back to school in the autumn, but sometimes they were replaced with babies the family had raised.
I once thought I would leave the vegetation intact as I was being assigned to the same classroom the next school year. I was shocked at how much water could evaporate in a room that had been closed up for two weeks. The good part was that the tank was then light enough to move home easily.

As vegetarians, pleco's have exceptionally short guts and like grazing mammals, feed near continually. So if water changes are not an issue, plan on visiting the school to feed the fish only as much as it will consume in a few hours, at least every other day, with a water change weekly.

The fish will survive on a near starvation diet far longer than it will fouled water and why I don't recommend those so-called "vacation" feeders, because they tend to foul the tanks. Another and better option would be an automatic feeder in which you could load bottom feeder pellets.

Then, you could set it to release small amounts of food several times daily, but only as much as the fish can eat in an hour or so, which is far safer than loading up the tank with several day's worth, because it would also foul the tank.

That might be you best solution. Then, a twice weekly visit to check on the tank, with one for a water change. Plecos seem as if they would be tough fish and when it comes to holding their own when kept in tanks with aggressive species they are, but they are also quite sensitive to water conditions.

Is the location going to have air conditioning over the summer?

I would give first pause to how hot it will get in the classroom, then worry about feeding and water quality.