Science at key stage 3    (Year 7)

• identify forces, eg magnetic attraction, friction
• use a forcemeter
• explain the observations they make, eg the plastic string is smoother so there is less friction and it is easier to untie

• state that all the objects weigh less in water than in air
• explain their observations in terms of an upward force from the water 'cancelling out' some of the downward force of the weight
• recognise that objects which float show a zero weight reading
• state that an object will float in water if it is less dense than water

• make measurements which enable them to test the claim
• evaluate their methods
• state that some liquids produce a greater upthrust on an object than others

• identify the forces on an object and the direction in which they are acting
• demonstrate understanding that forces on a stationary object, eg upwards and downwards, are equal

• represent the collected data on an appropriate line graph
• explain how they decided on their line of best fit, using repeated measurements and identifying anomalous results
• describe and compare relationships shown by the graphs, eg with the spring, every time you add 0.1N it extends another 0.5cm, but with the rubber band the prediction is more difficult

• identify the forces which are balanced in a range of situations
• use arrows to scale to show situations in which forces are balanced

• distinguish between mass and weight
• record measurements of mass and weight in appropriate units
• describe and use the relationship between mass and weight, eg on Earth a mass of 1kg has a weight of about 10N

• explain differences in behaviour in terms of differences in frictional forces
• identify characteristics of lubricants, eg often liquid, smooth, and explain their action, eg smooth out rough surfaces

• identify factors, eg weight, surface area, that might affect the frictional force between two surfaces
• identify and explain which variables need to be kept constant in order to obtain reliable data
• plot a suitable graph from their data and explain what it shows
• make and test a quantitative prediction from a graph

• describe examples where frictional forces are helpful
• explain why friction is important in the movement of vehicles
• present information about friction clearly and concisely

• identify that, for a given car, the stopping distance relates to its speed
• explain in words the units of speed, eg mph, km/h
• describe the journey shown in a speed/time graph, eg for the first ten minutes he didn't go very far, about a quarter of a mile, but in the next ten minutes he went four miles, so he probably got a bus or a lift

• identify, and draw representations to show, useful frictional forces, eg at brakes, and unhelpful frictional forces, eg at wheel axles
• make appropriate links and explain their reason for them