Another Way to Climb a Tree — Liz Garton Scanlon

When Lulu's feeling well, she climbs every tree in sight, especially
the tallest ones,
the ones with the widest branches,
the ones with the stickiest sap.

But when Lulu's sick, she's not allowed outside. She wonders if the trees are lonely without her. Maybe the birds are too.

Without Lulu, nobody climbs the trees but the sun ... which casts a shadow on Lulu's wall ... for her to climb.