Physical science

Chemistry: matter, change, and evidence.

Chemistry is the study of what things are made of and how they change. Students learn to separate observation from inference and to keep units on every measurement.

Particles and conservation

States of matter are explained with particle spacing and motion, not only with ice-water-steam pictures. Conservation of mass is a classroom experiment: mass before and after a precipitation reaction in a closed bag. If the bag is open, gas can escape — that is a teaching moment, not a failed lab.

The periodic table is a map of repeating properties. Groups, periods, metals, and nonmetals are enough for middle school; high school adds electron patterns in qualitative language before heavy calculation.