Lots of popsicle sticks
Glue (white or hot glue)
Ribbon
Green marker
Break a bunch of the popsicle sticks into two pieces. Try to break them at different spots to get different sizes
Sort the stick pieces from smallest to largest
Use one, whole, popsicle stick as the tree truck and glue it to the sorted sticks to make a tree
Add ribbon, colour the tree green, and maybe even add some Christmas decorations from supplies you have around the house.