Start with a piece of blue construction paper and use school glue to coat the the bottom 2 inches of the paper. Use gold glitter to create the ocean floor. If glitter is not available, cut a strip of yellow or sand-colored construction paper and glue that to the bottom of the paper. Let the kids take small pieces of tissue paper in various colors and crinkle them up. Glue them to the ocean floor to become their coral reef. Use crayons or colored chalk to make creatures for their ocean scene.
Starting with the same ocean background, create a scene of fish. Cut a "pie slice" from each circle to create the mouth of the fish. Glue the tip of the slice to the back of the circle to create the fish tail. Attach a googly eye to each fish. Glue scraps of tissue paper to the fish or color it with crayons, markers or decorate with glitter and sequins. Glue fish into the scene.
For younger children, consider a simple tissue craft. Start with a basic ocean background and give them their choice of tissue papers. Have the children layer tissue papers on the construction paper background with liquid starch. Once the starch has dried, allow them to use crayons or stickers to craft their own underwater scene.
For something a little more complex, have the kids put the ocean background into the back of a box to create a diorama. Have each child cut out pictures of various fish and ocean creatures to attach with string to the top of the box so they “swim” in the ocean. Glue small rocks and shells to the base of the diorama and enjoy the three-dimensional ocean scene.