“Expansion, Contraction & State Change” is a curriculum-aligned resource for Grade 7 Ontario Science (2022), supporting Strand C: Heat in the Environment. This resource explores how thermal energy affects the motion of particles, leading to observable changes in matter — including expansion, contraction, and changes of state. Students will build on their understanding of particle theory, learning how increased or decreased heat energy causes solids, liquids, and gases to behave differently. T