3-Aut2-C

Outcomes

• Pupils can arrange all the GCSE quantities into two groups: scalars and vectors.
• Pupils appreciate that force is a vector quantity and understand the nature of this.

Specification References

• 1.10 distinguish between vector and scalar quantities
• 1.11 appreciate the vector nature of a force

Starter

• Introducing the idea of vectors to the class. Here are two options.
• 1) Hide a £1 coin a set distance from a pre-determined place in the classroom. Stand on this spot with a stop watch. Choose two students and tell them "There is a £1 coin 2 meters from my current position. If you can find it within 6 seconds it's yours!" Stop the students after the 6 seconds. Encourage the students to discuss your statement. Is there enough information included in the statement to find the £1 coin? The displacement required to find the coin has not been fully described. Now, tell them " There is a £1 coin 2 meters and directly North of my current position, start the stop watch again. They will hopefully find the coin this time. You could even tape it to the ceiling if you wish! This statement now provides a complete description of the displacement vector - it lists both magnitude (2 meters) and direction (North) relative to a reference or starting position. Vector quantities are not fully described unless both magnitude and direction are listed.
• 2) Ask the pupils to estimate the number of steps you need to take to reach the back of the classroom. Once you have an agreed number of steps from the class begin walking to the back of the room (counting the number of steps as you go along) but walk in and out of the desks. Question how the pupils could have gotten it so wrong and begin to introduce the terms distance and displacement and how vector quantities are not fully described unless both magnitude and direction are given.
• Next, split the class into groups of six and give each group a pack of cards which contain all the GCSE quantities. Ask them to divide them into two groups: 1) those that have a direction and can be represented with an arrow (a vector) and 2) those that do not (a scalar).
• These cards should be left while they carry out work on the force table.

Main Body of Lesson

• Discuss the groups outcomes and write definitions for vectors and scalars to be recorded in their books. Emphasise that vector quantities could be negative whereas scalar quantities cannot. (They may argue about temperature where they can be introduced to the Kelvin scale)
• The groups will reassess their vector and scalar groups after the powerpoint.
• Discuss the images and have the class help label the forces using arrows. Guide them towards the correct direction of arrow and type of force as revision from the 3rd year. Begin looking for pairs of forces which are balanced and result in zero force on the object.
• Explain that force vectors are depicted as arrows to show the direction, with the length of the arrow representing the magnitude of the force. You could introduce the 'head' and 'tail' of the force vector.

Plenary

• Vector Addition Game Print A3 sheet from Science shared in FAD-01 folder
• Supply the pupils with large squared paper with the same starting point/'Home Base' and end point/ 'Base One' labelled.
• Following the two rules they are to draw a route from the Home Base to Base One. Emphasise that they are not to hugely complicate the journey. Don't forget to put arrows on each section of your journey.
• Rule 1 - They can only move vertically or horizontally.
• Rule 2 - Each section must be a whole number of squares.
• Invite six to eight pupils to come to the front of the class with their journeys (It would be better to select a group with a range of journey distances). Tell the class that you will be asking them to add the vectors up and can they order the pupils from largest vector displacement to smallest vector displacement.
• Ask them to now add all their horizontal and vertical vectors being sure to pay attention to their direction. Ask them to write their answers on the white boards in the form of (x,y). When they are all finished ask them to hold the whiteboards up together. Why are they the same?
• Ask them to now draw the shortest possible route in a different colour pen. Remind them of the rules! What do they notice?
• Ask them to now draw another route, in another colour, 'as the crow flies', obviously ignoring the rules.
• Emphasis that the three sets of vectors all result in the same displacement. If there is time and the class is able enough you could ask them to find the hypotenuse from sum of the squares of the two smaller sides which they could go onto measuring and verifying.

Homework

• Students could also research the difference between speed and velocity and how the change in velocity can occur by the velocity only changing direction and not magnitude. This could lead them to the idea of circular motion.

Resources Required

• Class set of quantity cards in envelopes + whiteboards
• Class set of mini whiteboards

Textbook References

• None

Website References

• None

Safety/Hazards

• None

Notes

• None