Cut a head band out of the green poster board that is slightly larger than the child's head.
Cut a hat shape out of the green construction paper.
Cut a 2 inch black strip. Glue onto the hat above the brim and trim the edges to align with the slant of the hat.
Cut a yellow square that is slightly taller than the black strip. Cut the center out of the square leaving 1/4 of an inch boarder. Glue on the middle of the black strip.
Tape the hat to the headband (it works better than gluing it).
Tape or staple the head band so that it fits around the child's head. Cut off any excess.