Lesson plan

Physical changes in Buttered popcorn

Make butter and popcorn, discussing the physical changes in each. Act out what the molecules are doing as popcorn pops.
Science content
Chemistry: States of Matter, Properties of Materials (K-7)
Chemistry: Physical Changes, Solutions, Mixtures and Separating (2, 4, 5, 6)

Materials in the activities


Act out molecules, so that students are familiar with what the particles are doing in solids, liquids and gases.

Make butter in a circle together, describing each stage in physical terms.
Cream has fat molecules floating in a watery white liquid (the white is casein protein clumps).
Shake the cream in a jar, to shake in air bubbles. Whipped cream is formed (open the jar to show). The molecules are the same but are reorganized - there are now bubbles of air molecules mixed in with the fat and water molecules of the cream.
As we shake more, the fat molecules in the cream gather together to make one big lump - butter!
The proteins and milk sugar molecules mix in with the water molecules, to make 'buttermilk'.

Make popcorn.
While the teacher is preparing the popcorn, first watch video of popcorn kernals bursting open in slow motion, then students prepare a skit to show what the molecules are doing as popcorn pops.
Watch the skits.

Dump the popcorn in a large bowl to salt it, and put the butter in the still-warm pot to melt it.
Distribute popcorn in little cups, with a small amount of melted butter poured over each.

Grades taught
Gr 2
Gr 3