Lesson 3: Refraction

1. Date Lesson 3: Refraction Connector: (Level 4) Explain that light bending at the surface of glass or water can deceive us Look at the set up of a straw in a beaker, draw what you see

2. BIG picture • What skills will you be developing this lesson? • ICT • Numeracy • Literacy • Team work • Self management • Creative thinking • Independent enquiry • Participation • Reflection

3. HOW SCIENCE WORKS • How is this lesson relevant to every day life? (WRL/CIT)

4. Bending light air glass The speed of light waves depends on the material they are travelling through. air = fastest glass = slower diamond = slowest If light waves enter a different material (e.g. travel from glass into air) the speed changes. This causes the light to bend orrefract.

7. New Information for Task 1

8. Task 1 (Level 5) • Task 1: • Task 1: • Label diagram using key words • Explain why light gets refracted • Keywords for Task 1: • angle of incidence • Angle of refraction • Normal

9. Task 1: Answers Light gets refracted as it slows down, light travels fastest through air, and slower through glass. The change is speed causes the light to bend.

10. Task 1: Review Go back to your lesson outcome grid and fill out the ‘How I did’ and the ‘Targets’ column.

11. New Information for Task 2

13. incident light ray semi-circular glass block refracted light ray normal angle measured here

14. Task 2 (Level 6) • Carefully mark the angles on the sheet of paper, making sure that they are lined up with the centre of the flat side of the glass block. • Shine the light accurately along the first line so that the light ray hits the centre of the glass block. • Mark the line of light that comes out of the curved side of the glass block accurately, using a ruler, • Measure the angle between the straight through line and each light ray. • Record results • Draw a grph • Keywords for Task 2: • refraction • Light • Bends • Angle • ray

15. Task 2: Answers

16. Task 2: Review Go back to your lesson outcome grid and fill out the ‘How I did’ and the ‘Targets’ column.

17. New Information for Task 3

18. Task 3 • Cut a piece of graph paper in two. • 2 Put one of the pieces of graph paper under an empty beaker. • 3 Place the second piece of graph paper next to the beaker. • 4 Look from above. You will notice that the squares on the graph paper look about the same size as each other. • 5 Now half fill the beaker with water and look again. • 6 Draw what you see. Pay particular attention to the size of the squares on the two pieces of graph paper. • 7 Now slowly lift the piece of graph paper that is next to the beaker until the sizes of the squares look the same (you need to keep this piece of graph paper next to the beaker). • 8 Measure the depth of the water and the distance from the surface of the water to the lifted piece of graph paper. • 9 Try steps 5–8 again with the beaker full of water.

19. Task 3: (Level 7) • Task 3: • Use the data to explain which material caused the most refraction • Task 3: Extension • Keywords for Task 3: • refraction • incidence • angle

20. Task 3: Answers

21. Task 3: Review Go back to your lesson outcome grid and fill out the ‘How I did’ and the ‘Targets’ column.

22. Homework • Homework task: • Due date: • Criteria for level 5: • Criteria for level 6: • Criteria for level 7:

23. Review of lesson • This is the answer what was the question? • Incidence • Refraction • Ray • Light • Glass • diamond