Go to the bag outside the cabin and get the sleeping pill formula, three drops of stagnant water, two drops of green medicine and four drops of green medicine. There are two places to refresh the dropper, one is the trolley outside, the other is the shelf outside the greenhouse, and then take the dropper into the classroom through the activatable channel. One of the classrooms has a flask or something, which can be dripped with a dropper. Pay attention to take one medicine and three sleeping pills at a time. One is the stagnant water in the toilet, the other is the ink in the hole in the classroom table, and the other is the green medicine in the cupboard on the second floor. You can pick up the flask containing sleeping pills, but it won't be used when you are fully prepared.