Heat the oven to 450 degrees F. Slice each pita into 8 even triangular pieces and then tear each piece apart at the seam to get a total of 32 pieces. Toss the pieces in a large bowl with the oil, 1/4 teaspoon salt, and some pepper. Spread in a single layer on a large baking sheet. Bake, flipping after 5 minutes, until the chips are crisped and slightly browned, about 7 minutes total.