1000 * 1/2 = <<1000*1/2=500>>500 students were taken on a trip to the nearby beach.
So 1000 - 500 = <<1000-500=500>>500 students were not taken to the beach.
Thus, 1/2 * 500 = <<500*1/2=250>>250 students who were not taken to the beach were sent home.
Thus, 500 - 250 = <<500-250=250>>250 students are still in school.
#### 250