1. PRO Physical Changes: declarative premiseο
Why does ice melt when it is heated?
Premise (P): The heating of a solid increases the kinetic energy of its particles.
Reasoning (R): As a result, the particles vibrate more strongly and eventually overcome the forces holding them in fixed positions.
Outcome (O): Therefore, the ice changes state into a liquid.
Why does a metal rod become longer when heated?
Premise (P): Heating a material increases the kinetic energy of its particles, causing greater separation.
Reasoning (R): As a result, the particles vibrate more and push against each other with greater force, increasing the spacing between them.
Outcome (O): Therefore, the metal rod expands and becomes longer.
Why does modelling clay change shape when it is pressed?
Premise (P): Modelling clay is a soft solid in which particles can slide past each other under an applied force.
Reasoning (R): As a result, the applied force causes the particles to shift into new positions without breaking the material.
Outcome (O): Therefore, the clay changes shape but remains the same substance.
Fill in the Gaps β Boiling Water
Complete the Outcome (O).
Why does water turn into water vapour when it is boiled?
Premise (P): Heating water provides energy that allows liquid particles to move rapidly and overcome intermolecular forces.
Reasoning (R): As a result, the particles move farther apart and escape from the surface of the liquid.
Outcome (O): __________________, the liquid changes __________________ into a gas.
Reveal Answer Key
Premise (P): Heating water provides energy that allows liquid particles to move rapidly and overcome intermolecular forces.
Reasoning (R): As a result, the particles move farther apart and escape from the surface of the liquid.
Outcome (O): Therefore, the liquid changes state into a gas.
Fill in the Gaps β Stretching a rubber band
Complete the Reasoning (R).
Why does a rubber band stretch when pulled?
Premise (P): A rubber band consists of long, coiled polymer chains that can uncoil under force.
Reasoning (R): __________________`, the force straightens and extends these __________________ without breaking them.
Outcome (O): Therefore, the rubber band becomes longer but remains the same material.
Reveal Answer Key
Premise (P): A rubber band consists of long, coiled polymer chains that can uncoil under force.
Reasoning (R): As a result, the force straightens and extends these chains without breaking them.
Outcome (O): Therefore, the rubber band becomes longer but remains the same material.
Fill in the Gaps β Snapping chalk
Complete the Premise (P).
Why does a piece of chalk break when you bend it?
Premise (P): The rigid structure of __________________ prevents particles from moving under a __________________ force.
Reasoning (R): As a result, the particles separate instead of shifting.
Outcome (O): Therefore, the chalk breaks into smaller pieces without changing its substance.
Reveal Answer Key
Premise (P): The rigid structure of chalk prevents particles from moving under a bending force.
Reasoning (R): As a result, the particles separate instead of shifting.
Outcome (O): Therefore, the chalk breaks into smaller pieces without changing its substance.
Fill in the Gaps β Fixed shape
Complete the Explanation by filling in the missing words (processes).
Word list (A β Z): deform, flow, move, spread
Why does a solid keep its shape?
Premise (P): A solid has particles that are tightly packed and held in fixed positions.
Reasoning (R): As a result, the particles cannot __________________ freely, so the solid cannot __________________ or spread out like a liquid or gas.
Outcome (O): Therefore, a solid keeps its shape unless a force strong enough to __________________ it is applied.
Reveal Answer Key
Premise (P): A solid has particles that are tightly packed and held in fixed positions.
Reasoning (R): As a result, the particles cannot move freely, so the solid cannot flow or spread out like a liquid or gas.
Outcome (O): Therefore, a solid keeps its shape unless a force strong enough to deform it is applied.
Fill in the Gaps β Melting butter
Complete the Explanation by filling in the missing nouns.
Word list (A β Z): energy β’ liquid β’ particles β’ positions β’ solid β’ state
Why does butter melt when it is heated?
Premise (P): Heating a solid increases the kinetic __________________ of its particles.
Reasoning (R): As a result, the __________________ vibrate more strongly and begin to loosen from their fixed __________________.
Outcome (O): Therefore, the __________________ changes __________________ into a __________________.
Reveal Answer Key
Premise (P): Heating a solid increases the kinetic energy of its particles.
Reasoning (R): As a result, the particles vibrate more strongly and begin to loosen from their fixed positions.
Outcome (O): Therefore, the solid changes state into a liquid.
Fill in the Gaps β Squashing a sponge
Complete the Explanation by filling in the missing adjectives or adverbs (modifiers).
Word list (A β Z): flexible β’ high β’ rigid β’ soft β’ strong β’ tightly
Why does a sponge compress when you squeeze it?
Premise (P): A sponge has particles that are not tightly packed and can move easily.
Reasoning (R): As a result, the particles shift, and the sponge bends because it is __________________.
Outcome (O): Therefore, the sponge becomes smaller under __________________ pressure.
Reveal Answer Key
Premise (P): A sponge has particles that are not tightly packed and can move easily.
Reasoning (R): As a result, the particles shift, and the sponge bends because it is flexible.
Outcome (O): Therefore, the sponge becomes smaller under high pressure.
Fill in the Gaps β Wet mirror
Complete the Explanation by filling in the missing text connectives.
Word list (A β Z): As a result β’ Therefore β’ When
Why does water form on a bathroom mirror?
Premise (P): Water vapour loses energy upon contact with a cooler surface.
Reasoning (R): __________________, the particles slow down and change state from gas to liquid.
Outcome (O): __________________, tiny droplets form on the mirror.
Reveal Answer Key
Premise (P): Water vapour loses energy upon contact with a cooler surface.
Reasoning (R): As a result, the particles slow down and change state from gas to liquid.
Outcome (O): Therefore, tiny droplets form on the mirror.
Fill in the Gaps β Overnight frost
Complete the Explanation by filling in the missing text connectives.
Word list (A β Z): As a result β’ Therefore β’ When
Why does frost form on grass overnight?
Premise (P): Air temperature below freezing allows water vapour to change directly into ice.
Reasoning (R): __________________, the particles lose energy and form ice crystals.
Outcome (O): __________________, frost forms on the grass.
Reveal Answer Key
Premise (P): Air temperature below freezing allows water vapour to change directly into ice.
Reasoning (R): As a result, the particles lose energy and form ice crystals.
Outcome (O): Therefore, frost forms on the grass.
Fill in the Gaps β Cold to touch
Complete the Explanation by filling in the missing verbs (material processes).
Word list (A β Z): conducts β’ feels β’ loses β’ move β’ transfers
Why does a metal spoon feel cold in winter?
Premise (P): Metals conduct heat efficiently, allowing thermal energy to transfer quickly.
Reasoning (R): As a result, your hand __________________ warmth as heat __________________ away into the metal.
Outcome (O): Therefore, the spoon __________________ cold to touch.
Reveal Answer Key
Premise (P): Metals conduct heat efficiently, allowing thermal energy to transfer quickly.
Reasoning (R): As a result, your hand loses warmth as heat transfers away into the metal.
Outcome (O): Therefore, the spoon feels cold to touch.
Fill in the Gaps β Clothing in wind
Complete the Explanation by filling in the missing describers (adjectives/adverbs).
Word list (A β Z): faster β’ liquid β’ moving β’ moist β’ more
Why does wet clothing dry on a windy day?
Premise (P): Moving air removes water vapour from the surface of a liquid.
Reasoning (R): As a result, __________________ liquid water can evaporate because the __________________ air above is removed.
Outcome (O): Therefore, the clothing dries __________________.
Reveal Answer Key
Premise (P): Moving air removes water vapour from the surface of a liquid.
Reasoning (R): As a result, more liquid water can evaporate because the moist air above is removed.
Outcome (O): Therefore, the clothing dries faster.
Fill in the Gaps β Disappearing puddle
Complete the Explanation by filling in the missing verbs (material processes).
Word list (A β Z): absorbs β’ changes β’ evaporate β’ gain β’ rise
Why does a puddle disappear on a sunny day?
Premise (P): Solar energy increases the kinetic energy of water particles in a puddle.
Reasoning (R): As a result, the particles move faster, break free from the liquid, and __________________ into water vapour.
Outcome (O): Therefore, the puddle disappears as the liquid __________________ into a gas.
Reveal Answer Key
Premise (P): Solar energy increases the kinetic energy of water particles in a puddle.
Reasoning (R): As a result, the particles move faster, break free from the liquid, and evaporate into water vapour.
Outcome (O): Therefore, the puddle disappears as the liquid changes into a gas.
Shrinking a balloon
Explain the following phenomenon using the PRO structure.
Why does a balloon shrink when placed in the freezer?
Reveal Answer Key
Premise (P): Lower temperature reduces the kinetic energy of gas particles.
Reasoning (R): As a result, the particles move more slowly and occupy less space.
Outcome (O): Therefore, the balloon becomes smaller in the freezer.
Sun dried towel
Explain the following phenomenon using the PRO structure.
Why does a wet towel dry when left in the sun?
Reveal Answer Key
Premise (P): Heat energy increases the kinetic energy of water particles in a wet material.
Reasoning (R): As a result, the particles move faster and escape into the air as water vapour.
Outcome (O): Therefore, the towel becomes dry.