How safe are your sunglasses?

How safe are your sunglasses?

Pencil and paperOnline interactive
Overview
Using this Resource
Connecting to the Curriculum
Marking Student Responses
Working with Students
This task is about how light effects the eye and the use of sunglasses.
sunglasses.png
Read the information that follows and use it to answer the questions. 

Question

a)  i)  Which diagram shows what the eye would look like in bright light?
    • Smallpupil.png

    • Bigpupil.png

Explain your answer.

Question

     ii)  Which diagram shows what would change if you were wearing sunglasses?  
    • Smallpupil.png

    • Bigpupil.png

Explain your answer.

Question 1Change answer

Here is some information about choosing sunglasses that are safe:
  • All sunglasses stop some sunlight from reaching the eyes.
  • Only some sunglasses also stop ultraviolet light (UV) from reaching the eyes.
   
b)  UV light can "sunburn" the retina causing temporary blindness. Scientists say it is dangerous to wear sunglasses that do not filter out UV light. Explain why scientists would say this about sunglasses, using:  
  • the information in the box, and
  • your own understanding of how the eye is protected from bright light.

Question

How can you tell which sunglasses are safe?

  • It is possible to test the amount of UV that can get through sunglasses.
  • There is a "safety standard" that sets the amount of UV it is safe to let in. This is either 99% or 100%. If they qualify, sunglasses have to display this safety sticker in Australia. It is not yet compulsory in New Zealand.
  • Cost is no guide to safety. Some cheap sunglasses are safe and some expensive ones are not.
 
c)  Who would be the best people to test and check sunglasses to see if they are safe?
    • the people who wear them

    • the people who sell them

    • technicians in testing laboratories

    • scientists who investigate eye safety

Explain your answer.

Question

d)  Who are the best people to set the safety standard for sunglasses? 
    • the people who wear them

    • the people who sell them

    • technicians in testing laboratories

    • scientists who investigate eye safety

Explain your answer.

Question 1Change answer

Some sunglasses are designed to be worn in places where people are at risk of getting too much UV over a long period of time. These glasses cut out much more light than ordinary sunglasses. If the retina gets too much UV for too long it can become damaged so badly that the person goes permanently blind. In Australia, they carry a safety sticker that looks like this.
e)  What do you think the safety sticker means?
     
 
f)  Why would glasses that cut out a lot of light need a sticker like this?
     
Task administration: 
This task can be completed with pencil and paper or online (with SOME auto marking).
Level:
5
Description of task: 
Task: Demonstrate understanding of the pupil reflex of the eye, and apply this to answering questions about sunglasses safety. Extension questions probe understanding of who decides on and applies safety standards. Assessment focus: effect of UV light on the eyes and how it can be mediated by simple sunglasses technology.
Curriculum Links: 
 
 

Science capabilities
The capabilities focus is brought about by the conversations you have and the questions you ask 
Capability: Use evidence
This resource provides opportunities to discuss that, when deciding a material’s suitability for a given task, sometimes the properties have to be prioritised.
 

 

Science capabilities: 
Answers/responses: 
 

Y10 (07/05)

a)

 

i)
ii)
A (diagram shows small pupil relative to B)
B (diagram shows larger pupil relative to A)
easy
easy
b)  
Answers should include:
  • Ultraviolet eye causes damage to the retina
  • Explanation including how sunglasses will cut out light, the pupil will dilate and more UV light get to the retina increasing the potential damage
 
 
difficult
very difficult
c)   C difficult
d)   D easy
e)   Don’t drive while wearing these glasses. moderate
f)   Any explanation that links low levels of light entering eye to inability to see clearly enough to drive safely. moderate
Diagnostic and formative information: 

Common misconceptions in question b). These included:

  • Sunglasses can magnify UV light
  • UV light gets trapped in the sunglasses.
  • The whole eye gets bigger or smaller.
  • Wearing low quality sunglasses represents the same situation as wearing no sunglasses.
  • Confusion over the correct names for parts of the eye.

Indications of students' ability to explain and discuss
38 percent of the trial students answered question b) by essentially repeating the information provided, not adding any element of their own understanding to address the question. Very few students (6 percent) drew on their biological knowledge of the eye to introduce correct terms (e.g. "pupil") into their discussion. The question explicitly asks for students to use their own knowledge, and most correctly recognised the pupil reflex, so they did have some knowledge. This question could provide a useful opportunity for students to practise applying what they know to a new situation.


Knowledge of science/society interactions
Students appear to have very little understanding of the role of science and technology in determining safety standards:

  • 14 percent thought the people who wear sunglasses should test them to see if they are safe.
  • 6 percent thought the people who wear them should set the safety standard for sunglasses.
  • 6 percent thought the people who sell sunglasses should test them to see if they are safe.
  • 11 percent thought the people who sell them should set the safety standard for sunglasses.

Where students did recognise that these roles should be carried out by those with the knowledge and expertise (and lack of self-interest) to do so, they often confused the roles played by scientists and technicians.

  • 47 percent thought scientists should test sunglasses to see if they are safe.
  • 19 percent thought technicians should set the safety standard for sunglasses.

Links to the curriculum
A discussion of the issues raised by questions c) – f ) could help students link ideas about the role of science in setting and maintaining safety standards, to the integrating strands for the "nature of science" and for "participating and contributing" achievement objectives. Students could, for example, research how safety standards are devised and debated. This task also provides students with an opportunity to explore one way science is used to enhance public safety, in a situation where they could be expected to make good personal decisions now, or at any time in the future. This idea again links the question to the "participating and contributing" aim.

There are several avenues that could be pursued – either as next learning steps or as open questions in summative assessment.

  • Do students recognise that they can use the information about safety standards to guide their own decision-making? Would they do so? Why or why not? 
  • Safety standards for sunglasses are mandatory in Australia but not in New Zealand. Do students think they should be mandatory in New Zealand? Why or why not? An open discussion of this second question might reveal aspects of students' underlying values in relation to regulation of public safety. Students who believe every person should be be responsible for their own decisions and actions may be less inclined to support mandatory safety standards.