Sometimes when we work on things in science, they don't get completely done. Pockets in science notebooks are an easy way to store things for that purpose. Or to store a cardstock ruler, or some vocabulary cards. Or a candy bar. Whatever.
This one requires no extra product. Take two sheets of paper. Fold one over diagonally, glue the side and bottom to the second page. And eureka! there's a pocket.
For this one, you could use an envelope or a sheet of paper folded over. Just glue it to an inside cover or a sheet of paper.
This envelope is cut up the side and has the flap cut off.