Make meringues, find out what makes the foam in them. Make other foamy foods.
Science content (2016 curriculum):
Chemistry: States of Matter, Properties of Materials (K-7)
Chemistry: Atoms, Molecules (3-7)
Chemistry: Physical Changes, Solutions, Mixtures and Separating (2, 4, 5, 6)
Curriculum connection (2005 science topic):
Physical Science: Chemistry (grade 7)