If your child is able have them cut the tree out by folding the brown paper in half and cutting the trunk and branches.
Glue it down.
Talk about what colors you see in your yard and add some leaves by dabbing the pompom on the paper. Ask if the trees they see around their house have leaves on their branches or if they have all fallen. Ask if there are more than one place they could paint leaves to encourage decision-making and possible conversations about why leaves fall.
Emphasize that there is no wrong way to do this activity and that they do not need to match their tree to the examples outside unless they want to. Do not discourage color mixing. Color mixing is a great hands on experience for kids so let them explore. You might end up with a tree will all brown leaves and if that’s what your child makes then it’s rad.