Answers - John Buchan School

1. (a) Award TWO marks for all four statements correctly classified: 2The pictures show that as the corn pops, it...orgets bigger.changes to a darker colourchanges shape.gets smoother.TrueFalseIf you are unable to award two marks, award ONE mark for any two or 1three statements correctly classified.(b) Award ONE mark for: 1Sasha should measure the…temperature.(c) Award ONE mark for: 1heat(d) Award ONE mark for identifying/ describing a non-reversible change 1where a new material is produced, eg:• (wood/paper/candle) burning;• egg being boiled;• mixing vinegar and bicarbonate of soda;• cooking a cake/biscuits;• making a cake;• boiling rice/spaghetti;• making paper from wood/trees.♦ Give credit for a correct response that goes beyond the key stage 2programme of study which names a chemical change:• combustion;• corrosion/rusting;• respiration/photosynthesis.ONE mark may be awarded for identifying abiological non-reversible change:• an apple decaying/going rotten;• a seed growing into a plant.ONE mark may be awarded for a responseJohn Buchan Middle School 1

(b) Award ONE mark for describing a safety precaution that is shown in the picture: 1• she is using tongs;• the metal dish stops fire spreading;• the tray and sand (do not burn);• the short/small candle/nightlight is less likely to fall over;• she uses a safe flame;• there is sand around the candle.Allow:• use soil in the dish [in place of sand];• sand/(metal) dish/tongs.Do not give credit for an insufficientresponse indicating an alternative method ofkeeping safe that is not shown in the picture:• she wears goggles;• the teacher does the experiment.(c) Award ONE mark for correctly completing the table: 1MaterialDoes itburn?Is the changereversible?wood yes Nobread yes No(d)Award TWO marks for correctly identifying the only two materials that will burn:2• cardboard [given]cotton woolor• newspaperIf you are unable to award two marks, award ONE mark for correctly identifyingone of the materials.[5]John Buchan Middle School 3

3. (a) Award ONE mark for both rows of the table completed correctly: 1Material/Object Flexible Hard Transparentaluminium foilwax candlewooden rolling pinplastic food wrapglass(b) Award ONE mark for describing a use of foil that requires it to be flexible: 1• wrapping up food;• to bend it around food.ONE mark may be awarded for describing ause of foil where the need for it to be flexibleis implied:• to cook a chicken in it;• to put your sandwiches in;• to seal take-away cartons;• covering oven dishes.Do not give credit for an insufficientproperty that gives a use unrelated to beingflexible:• it does not burn in the oven.(c) Award TWO marks for all three correct boxes ticked: 2cooling waterfreezing waterinto icedissolving saltin waterorIf you are unable to award two marks, award ONE mark for ticking any two 1of the correct boxes.John Buchan Middle School 4

(d) (i) Award ONE mark for: 1• condensation.(ii) Award ONE mark for a response indicating that the water inside 1the pan evaporates:• the water evaporates;• the water inside the pan turns to water vapour (when the water boils);• it changes to a gas.ONE mark may be awarded for anobservation implying the water evaporates:• the water turns to steam.Do not give credit for a response thatincludes incorrect science indicating the gaswill disappear:• the water will turn to water vapour whichdisappears.Do not give credit for an insufficientresponse:• the water disappears;• the water boils;• the pan goes/boils dry;• steam;• it will turn into condensation;• water vapour.[6]4. (a) Award ONE mark for correctly completing all four rows of the table: 1Solidsoilvitamin tabletplastic beadssaltBeakerBDAC(b) Award ONE mark for a response indicating the solid dissolved: 1• salt/it dissolved;• it formed a solution.John Buchan Middle School 5

ONE mark may be awarded for a responsestating that the vitamin tablet dissolved if thepupil has identified that the vitamin tablet isin beaker C in part a).Do not give credit for an insufficientresponse that does not explain whathappened to the solid:• it disappeared.Do not give credit for an insufficientresponse:• it mixed with the water.(c) Award ONE mark for: 1• Beaker D.ONE mark may be awarded for:• vitamin tablet.(d) Award ONE mark for: 1(e) Award ONE mark for an indication that Safara should evaporate the water: 1• evaporate the water;• by evaporation.ONE mark may be awarded for a responseexplaining the beaker should be moved to awarmer place and/or left to dry:• move the beaker on to a (sunny/warm)window sill;• put the beaker on a radiator;• by heating it.John Buchan Middle School 6

Do not give credit for an insufficientresponse where it is ambiguous what isevaporating:• evaporate the mixture;• evaporate it [it refers to the salt].Do not give credit for an insufficientresponse:• filter the solution.[5]5. (a) Award ONE mark for both correct: 1The change is non-reversible.The bubbles evaporate. False .............True .............(b) Award ONE mark for all three materials correctly classified: 1Materialinside thebubblevinegarchalk rockSolid, liquid or gas?gasliquidsolid(c) Award ONE mark for: 1• limestone;• pumice.Allow:• chalk.[3]John Buchan Middle School 7

6. (a) Award ONE mark for: 1• dissolving• dissolves.• Give credit for a correct response that goes beyond the key stage 2 programme ofstudy:• a solution• it is a solute.Do not give credit for an insufficientresponse:• it sinks to the bottom• mixing [given].(b) Award ONE mark for classifying all three statements correctly: 1A gas is produced by the yeast.TrueA reversible change has happened.FalseThe balloon is flexible.True(c) Award TWO marks for a general comparison describing the relationship between the 2temperature of the water and the time taken for the balloon to stand up:• the higher the temperature, the less time it takes for the balloon to rise• the lower the temperature, the longer it takes for the balloon to stand up.orIf you are unable to award two marks, award ONE mark for two specificcomparisons describing the relationship:• a high temperature took a short time and a low temperature took a long time for theballoon to stand.Award ONE mark for a single comparison of the variables:• a hot temperature made the balloon stand up in a short time• the balloon took a long time to stand up when the temperature was low.Marks may be awarded for responses givingthe relationship between the temperature ofthe water and the effect on the time taken forthe balloon to stand up:• the warmer the water, the quicker theballoon rises• the hotter the water, the quicker gas wasproduced.John Buchan Middle School 8

Do not give credit for a response thatincludes incorrect science suggesting thatthe yeast rises:• the hotter the water the quicker the yeastrises.Do not give credit for a response thatincludes incorrect science, changing one orboth variables:• the hotter the water, the smaller the balloon• the hotter the water, the shorter time theballoon stays up for.Award ONE mark for a single comparison of the variables:• a hot temperature made the balloon stand up in a short time• the balloon took a long time to stand up when the temperature was lowDo not give credit for an insufficientresponse that does not interpret the results:• at 3°C it took 52 minutes, and at 50°C ittook 4 minutes.(d) Award ONE mark for: 1• noANDa response explaining that the mixtures at 20ºC and 30ºC did not cause the balloonto stand up most quickly:• the balloon blew up more quickly at 50ºC• the balloon blew up faster at a higher temperature than 20ºC or 30ºC• it took longer for gas to be produced at 20ºC and 30ºC than at 50ºC.Award ONE mark for:• noANDa response indicating that the yeast worksquickest at 50ºC or at a higher temperaturethan 20ºC or 30ºC:• it works quickest at 50ºC• at 30ºC it took 16 minutes but it only took4 minutes at 50ºC.John Buchan Middle School 9

ONE mark may be awarded if neither box isticked but a creditworthy explanationindicates that the pupil believes theinformation from the cook book is notsupported by the results of the investigation.Do not give credit if the ‘yes’ box is ticked.Do not give credit for an insufficientresponse that gives a continuous variablerelationship between the time to stand upand the temperature of the water:• the hotter the water, the quicker it takesto stand [does not give examples from theresults].Do not give credit for an insufficientresponse that only restates the results in thetable:• I know this because it was 4 mins at50°C, 18 mins at 20°C and 16 mins at30°C.Do not give credit for an insufficientresponse:• it is easier at higher temperatures [it isambiguous as to what easier refers to]• it is best at 50°C [best must be defined].Additional guidance[5]7. (a) Award ONE mark for an indication that the liquid is melted wax from the candle: 1• melted/liquid wax;• (candle) wax.Allow:• melted candle.Do not give credit for:• melted wick;• candle.John Buchan Middle School 10

(b)Award ONE mark for identifying the process:• melt(ing). 1Do not give credit for:• turns to liquid;• liquefies [this is what happens when gasis compressed];• liquidised/liquidate;• warming,• thaws.(c)Award ONE mark for a description of the mass decreasing:• the mass decreased/got smaller/ went down/got lower/got less/ went small. 1Allow:• it got lighter;• it dropped;• there's a loss of weight.Do not give credit for:• it got shorter.(d)Award ONE mark for an awareness that the products of burning cannot be changed back:• it's a chemical change;• you can't get the wax back;• it changed to a different material.Allow:• you can't re-use a candle after it has burned. 1Do not give credit for:• wax disappears;• the wax turned to a gas;• burning is irreversible [given];• the wax would have melted [this is aphysical change];• the wax has been changed;• it's like baking a cake [not specific].[4]John Buchan Middle School 11