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Scratch proof

  • Key Stage 3
  • Popular Activity
  • Topical

Type: Activity
Learning Strategy: Information retrieval
Topic: Bonding & structure

Mobile phone screens can get badly scratched in pockets full of loose change, keys and combs. A tough plastic film, developed in Japan, is set to make scruffy screens a thing of the past. It shrugs off ink and metals don't scratch it.

So what gives the plastic its amazing toughness? In this DART activity, pupils learn how a solid's properties depend on the forces holding the particles together.

Published: 5th January 2005
Reviews & Comments: 5

Learning objectives

Learning objective
Pupils will associate hard materials with particles that are firmly held together and explain why some materials repel water.

Try the activity

You will need Acrobat Reader installed to open the activity sheets.

QCA Unit 7G

Pupils should be taught how the particle theory of matter can be used to explain the properties of solids.

Running the activity

Timing: starter - 5 minutes; main 10 minutes; plenary 5 minutes

Suggested starter activity: Introduce the activity by talking about how annoying it is when your shiny new phone gets its first scratch.

Main Activity: Project page 1, which shows an advert for a scratchproof mobile and sets the task. Pupils need to write a report on the phone for a magazine's advice page. They will have to refer to "the Science" on Page 2 to explain how its protective coating works. Page 2 explains in terms of particles why some materials are harder than others and shows what makes a surface repel water.

Page 3 is the template for the pupils report and shows the main components of the phone's scratch-free coating. It's key features are that it is non-stick, because of its plastic matrix, and hard because it has microscopic spheres of silica embedded in the plastic.

As a plenary the class could brainstorm to come up with a list of other applications of this tough, non-stick coat. It is already being used on DVDs and variations on the formula are being developed for other applications, like windows that don't need cleaning.

News links

New Scientist
Super-tough coating for cellphones and discs: A New Scientist article describing the breakthrough in creating a scratch resistant coating for DVDs and mobile screens.
Armor Plated or Overrated?
Armor Plated or Overrated? An illustrated account of an experiment to compare the abrasion resistance of ordinary DVDs and discs with scratch-resistant coatings.
Hard materials
Exploring the material world: An excellent introduction to what makes materials hard using diamond, graphite and Kevlar as examples.

Reviews & Comments

Write your online review to share your feedback and classroom tips with other teachers. How well does it work, how engaging is it, how did you use it, and how could it be improved?

Scatch Proof Activity

Jun 20th, 2010

5 Star

used this as an extension task to develop ideas about the particle model past the usual s/l/g model - worked really well.

Reviewer: Chris Budd

Scratch proof review

Jul 15th, 2008

5 Star

Excellent- used as a stimulus for extended writing, some excellent written outcomes.

Reviewer: Michael Corbett

Scratch proof review

Apr 6th, 2008

5 Star

Haven't been able to use it yet but it's on standy by as it looks very promising

Reviewer: Gill Mulliss

Scratch proof, good for OCR National in Science!

Apr 26th, 2007

5 Star

I have just used this activity with 2 groups of Yr 10's following the new OCR National in Science. This fitted really well in getting them to think about the properties that materials can have. This normally hard to motivate group really enjoied thinking up of uses that the film could also have other than mobile phone screens. I would highly recommend it for the OCR course.

Reviewer: Lindsay Weller

scratch proof

Jul 2nd, 2005

4 Star

I carried out this activity with a top set yr 8 group.I only used sheets 2 & 3. I told them that they worked for a chemical company that had just invented a new compound for mobile phone screens. When they had filled in sheet 3 I asked them to "sell" their new product to a representitive of a phone company. When we finished this activity I told them that the product really did exist and we discussed further applications. The students reported that they learned "quite a lot" about plastic and diamond-like structures and how by putting different materials together you could get the best of both.

Reviewer: karen jeynes