A mortarboard refers to a traditional graduation cap that is completely flat at the very top with four corners. At the top there is usually a button from which a silk tassel hangs. According to the Yale Alumni Magazine, the mortarboard originated during the 17th century at Oxford University, where the donning of a square scholar's hat was allowed for very important members. The mortarboard you create can serve as a homemade decoration or make a younger member of a household feel more included in the graduation festivities.
Cut a piece of poster board into a perfect square, 8 inches by 8 inches. Cut an additional strip of poster board that measures 3.75 inches by 2 feet. Cut the strip to this length regardless if you're making a cap for a child or adult, as you'll be adjusting it later.
Cut a series of V-shaped notches into your 2-foot-long strip. Your notches should be 1 inch apart and approximately 1.5 inches high. Draw a dotted line that's perfectly straight just underneath all your notches.
Wrap the strip around the head of the person who will wear the mortarboard and mark where you need to staple the ends together to allow a comfortable fit. Make a firm crease along your dotted line. Staple the ends together at the place you marked. This is the part that will go around your head and attach to the mortarboard.
Dab craft glue to the top part of each folded-down notch. Press the folded-down notches onto the exact centre of your square piece of poster board. Allow to dry. This is how the mortarboard will balance on your head.
Cut a piece of cord that has a tassel attached at the end to 8 inches in length. You can find such a cord and tassel at any craft store and some fabric shops. Knot the un-tasselled end around the bottom of a brass tack fastener. Push the pointy end of the brass tack fastener into the middle of the flat part of the graduation cap, securing and flattening the ends of the tack from underneath.