Lesson Plan

5. Explain how water can bend light

06_06_05*

Learning Outcomes

Explain how water can behave as a lens

Higher: Is able to analyse and compare different water lenses
Middle: Can suggest examples of water acting as a lens
Lower: Is able to describe how water can act as a lens

Activities

Lesson Starter - Engage

Method:

Lesson Recap Starter: Think back to the last lesson. What is white light?

Lesson Starter: Have you noticed how things look different when you look at them in water or through a glass of water? Suggest reasons for this.

Ask pupils if they know anyone who wears glasses, if they have ever tried them on, and what they noticed when they did?

Resources:

Presentation - Starter Slide.

The Story - Explore and Explain

Method:

Students should experiment with a glass of water, looking through and making observations.  They should record the effects and write a very short report to summarise what they did, what they have observed, and what conclusions they draw from that small experiment.  Students should then answer questions and take part in activities during the  for the remainder of the presentation. 

Key Concept:

During this unit, each lesson contains a key concept question housed in the '30 Second Challenge' slide. To help children master this content so the knowledge moves from their short term memory to their long term memory, at the beginning of the follow on lesson the question from the previous lesson is revisited. 

The questions covered during this unit include:

1. How are shadows created? Why do shadows change during the day?

2. Why are transparent materials useful?

3. Provide three examples that explain the different uses of lenses.

4. What is white light?

5. Why does water bend light?

6. When is light colour mixing used in industry and how?

Resources:

Presentation

Lesson Expert - Explain

Method:

Expert Film: Chris Marriott explains how lenses in our eyes help us to see.

Talk about the lens behind the iris opening and closing letting more or less light in and the lens in an eye is like a magnifying glass being moved backwards and forwards adjusting the focus.

How we deliver the Gatsby Benchmarks:

2 - Learning from career and labour market information:  Pop along to Developing Experts career’s zone to find out about jobs in your area.

4 - Linking curriculum learning to careers: This unit showcases careers that relate to light. Access our 360° virtual work tours.

7 - Encounters with Further and Higher Education: Pop along to Developing Experts career’s zone to find out about training providers in your area.

Resources:

Presentation - Expert Film

Lesson Assignment - Elaborate

Method:

Glass of water lens

  1. Hold up an image of a left facing arrow.
  2. Then slide a cylindrical glass of water in front the image.
  3. Look through the glass and describe what you see.
  4. Then move the glass towards and away from the image and describe what you see.

Droplet Magnifier 

  1. Place a waterproof transparent material on top of a page of newspaper. Near the middle of the film, place a drop of water using a pipette or the tip of your finger.
  2. Next, carefully lift and hold the transparent material about 2cm above the newspaper.

Resources:

Glass of water lens

  • cylindrical glass of water
  • drawing of an arrow


Droplet Magnifier

  • small piece of waterproof transparent material i.e. cling film, acetate, clear acrylic, petri dish etc.
  • pipette
  • water

Lesson Log - Evaluate

Method:

Quiz  

With their talk partners, the children are to go through the quiz at the end of the presentation and answer the questions.

Resources:

Quiz in presentation

 

Assessment

Questions to Ask During the Lesson

Explain how water behaves like a lens?

Why does the water magnify images?

Choral Response Questions/ Phrase Suggestions

What does a lens do?

Choral Response Questions/Phrase Suggestions

A lens...  

Lenses are used to...

Teacher Mastery

The Science Behind the Science
The speed of light in a vacuum is constant (300 million meters per second) but the speed of light is less than this value when light travels through denser media such as air, water, plastic and glass. Lenses change the direction of light based on the principle of refraction, where light will change direction in relation to how its speed changes when moving from one transparent medium to another. Lenses are found in telescopes, microscopes, the human eye, spectacles, cameras and projectors.

A common material that behaves like a lens is water. For example, a straight straw placed in a glass of water will look different above the water compared to below the water when viewed from the side, making the straw look distorted or bent. This happens because light reflected from the top part of the straw (above the water) travels straight through the air to our eyes whereas light reflected from the bottom part of the straw (below the water) is refracted as it moves from the water to the air, causing the image of the straw to be in a slightly different place.

Curriculum Fields

National Curriculum

Use the idea that light travels in straight lines to explain that objects are seen because they give out or reflect light into the eye; explain that we see things because light travels from light sources to our eyes or from light sources to objects and then to our eyes; use the idea that light travels in straight lines to explain why shadows have the same shape as the objects that cast them

Working Scientifically Skills

Planning different types of scientific enquiries to answer questions, including recognising and controlling variables where necessary

CBSE

Grade 6 Light, Shadows and Reflection.

Chinese Compulsory Education Primary School Science

knows that light from the light source or reflected light from the object enters the eye & can make us see the light source or the object knows that when the moving light encounters an object the reflection phenomenon will occur & the direction of light propagation will change knows that light travels in a straight line in the air