At circle time, we brainstormed about how to paint the trees in the photo and even about how to position the now joined papers on table (with the sky towards the painter so that the trees are actually painted upside down.) After snack, the children got to work. The trees are painted with brown/black tempera. This paint was pulled from our glass easel paint jars and the water in it has mostly evaporated, leaving a pudding-like consistency (very thick).
Once the trees were finished, the two sides were folded on top of each other. Symmetry, not so much, but trees reflected in water...absolutely.