Using a pencil and a ruler, trace a triangle about 4 inches tall. Cut the triangle out of the cardboard to form the base of your tree.
Cut a tiny, ¼ inch notch in the side of the triangle towards the bottom. This will give you a place to secure the end of the yarn. Secure the end of the yarn and begin wrapping the yarn around the cardboard, making sure each layer sits close to the previous layer. Alternate directions while wrapping. Continue until the entire triangle is covered. Secure the other end of the yarn by wrapping it around the back and tucking it in the wrapped yarn.
Once the tree is fully wrapped, use dots of white school glue to attach pom poms as “ornaments” on your tree. Glitter pom poms can be added for some sparkle, but any pom poms will do.
Finish by sticking the foam star-shaped sticker to the top of your tree for a festive touch. Allow everything to dry thoroughly before displaying.