1 - Surely there is/are outside faucet/s. Did you look for a recessed type that is flat with the outside wall of the school - to avoid unapproved use, they don't have a handle to turn like those at home, but use a 'key' and are about 3" X 5", ours are chrome. You will see the spigot the hose is attached to and a shaft sticking out, usually square for the key. Did you ask the custodian or office? . . . 2 - Use mulch or ground cover plants such as creeping phlox (perennial), it blooms in the spring when the students are there, or there are many types of ground cover perennial sedums which also bloom in the spring, or plastic. With the ground cover perennials you can also work in annual plants. . . . Our custodians also don't do flower work, in parks or schools, I guess they think of them as non-essentials and if citizens plant them, they should also maintain them, but some watering, especially in the bad heat when noone is around the schools would be nice.