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21st century skills activity · IGCSE 0625 · 1.4 Density

Density: cards to cut out

Print, then cut along the dashed lines. The prediction card opens the lesson with Think, Pair, Share. The role cards set up Rally Coach, and the eight problem cards drive the paired practice. The answer for the checking partner is printed at the foot of each problem card.

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The prediction card

One per pair, for the hook

Prediction card · Think, Pair, Share

Here are two cubes of the same size: one aluminium and one steel. Which has the greater mass?

Think alone for thirty seconds, then complete this sentence:

I think the ____________ cube has more mass because ________________________________

Compare with your partner, then be ready to share.

Role cards for Rally Coach

One solves, one coaches, then swap

Partner A solves out loud while partner B coaches and checks each line; they swap roles every card.
Swap roles after every card

Solver

  • Work one problem out loud.
  • Write down every step as you go.
  • State the unit in your answer.

Coach

  • Watch and check each line.
  • Give a tick or a hint, never the answer.
  • Then swap roles for the next card.
Rally Coach problem cards

Eight cards, building to the stretch

Partner A takes the odd numbered cards, Partner B the even, swapping the solver and coach roles each time. The set builds from direct calculations, through the rearrangements and a unit conversion, to one stretch card on comparing liquids.

Card 1find density

A block has a mass of 240 g and a volume of 30 cm³. Find its density.

Coach check: 8.0 g/cm³
Card 2find density

A plastic cube has a mass of 18 g and a volume of 24 cm³. Find its density.

Coach check: 0.75 g/cm³
Card 3find mass

Lead has a density of 11.3 g/cm³. Find the mass of a 5 cm³ piece.

Coach check: 56.5 g
Card 4find mass

Water has a density of 1.0 g/cm³. Find the mass of 250 cm³ of water.

Coach check: 250 g
Card 5find volume

An object has a mass of 60 g and a density of 2.4 g/cm³. Find its volume.

Coach check: 25 cm³
Card 6find volume

A steel part has a mass of 158 g. Steel has a density of 7.9 g/cm³. Find its volume.

Coach check: 20 cm³
Card 7convert units

Convert a density of 0.8 g/cm³ into kg/m³.

Coach check: 800 kg/m³
Card 8stretch: compare

Oil (0.92 g/cm³) and water (1.0 g/cm³) do not mix. Which floats on top, and why?

Coach check: oil floats: it is less dense than water
Original work by the TheLucidSTEM team. Written in the style of the papers; no past paper question is reproduced.
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