Compare the warmth of a sunny spot to a shady spot and connect the difference to sunlight.
Sunlight warms things up. Shade is a spot blocked from direct sunlight, and it usually stays cooler. You can feel this difference yourself just by touching two different spots outside.
A grown-up should always check first whether a sunny surface, like dark pavement, is too hot to touch safely.
Mastery looks like: They correctly predict and confirm by touch that a sunny surface feels warmer than a shaded one, safely checked by a grown-up first.
Common stumbles: Touching a sunny surface without a grown-up checking it is safe first; confusing air temperature with how hot a surface itself feels.