Squashing, bending, twisting and stretching
Chemistry · Key Stage 1 · The School
Four things you can do
SQUASH, BEND, TWIST, STRETCH. Try each on a piece of playdough, a sponge, a rubber band, a paper clip and a wooden lolly stick. Not everything will do all four — a lolly stick snaps rather than bending far, and that is a result worth writing down.
Springing back, or not
A rubber band stretches and returns. Playdough stays where you put it. Materials that return are ELASTIC; materials that stay are not. Sort your objects into two piles on that basis and see which pile is bigger.
Why it matters
A bridge must not bend much. A trampoline must. A paperclip has to bend and STAY bent, or it would spring off your papers. Engineers pick materials for exactly this property, and getting it wrong is how things break.
Roll dough into a sausage. SQUASH it by pressing from both ends: it gets shorter and fatter. Take a new sausage and STRETCH it by pulling the ends: longer and thinner. BEND another into a U: same length, curved. TWIST the last by turning the two ends opposite ways: it spirals. Four actions, four different results from identical starting shapes — which is why they get four different words.
Does it go back?
Squash a sponge and it springs back. Squash a lump of clay and it stays squashed. That difference has a name worth knowing: a material that returns to its shape is ELASTIC, and one that keeps the new shape is not. Test a few things and sort them into two piles — a rubber band, a paper clip, a piece of dough, a sponge, a drinking straw. The paper clip is the interesting one, because a small bend springs back and a big bend does not. Almost every material behaves that way if you push it far enough.