UPD8

Testing ion claims

Learning objectives

Students will:
• Evaluate plans to test claims made by the makers of IonX and Trion:Z.
• Design their own plans which would result in valid evidence.

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Curriculum link

How Science Works
2a Plan to test a scientific idea, answer a scientific question

GCSE specifications
AQA Additional
Unit Chemistry 2
• When atoms form chemical bonds by transferring electrons, they form ions. Atoms that lose electrons become positively charged ions. Atoms that gain electrons become negatively charged ions.

Edexcel Additional
Topic 6: In Your Element
• recall that an ion is an atom or group of atoms with a positive or negative charge.

OCR 21st Century Additional
Module C4: Chemical Patterns
• recall that an ion is an atom (or group of atoms) that has gained or lost electrons and so has an overall charge.

Running the activity

There are two alternative contexts for this activity: IonX sportswear, as worn by some World Cup rugby teams, and TrionZ wristbands. The planning task is common to both contexts. Each of the two activity pdfs gives the complete activity for one of these contexts. The page numbers below refer to both pdfs.

Starter (5 min)
Introduce either product by showing the relevant advert (see web links below). Then display page 1, which sets the scene and outlines the main tasks.

Main (30 min)
Give each pair of students a copy of page 2, which introduces the 'science' as explained on the company's web site. Ask them to discuss the questions in the bottom right corner of the page. Encourage them to focus on the 'science' behind the claims: how does the company claim the technology works? [Answers: IonX claims – increases speed, strength, power and speeds up recovery); TrionZ claims – decreases tiredness, increases concentration and eases joint and muscle ache]

Next, display page 3. Ask each group to identify 3 strong points and 3 weak points about the trial.

Possible answers:
IonX strong points:
• Blind trial
• Length of exercise is long enough (range)
• Big enough sample

IonX weak points
• Is pulse rate the correct output variable? What claim are they actually investigating?
• Players have varied fitness so starting condition is not controlled.
• Did all the players train at the same pace for the entire two hours?

TrionZ strong points
• Blind trial
• Investigating a claim that TrionZ has made (that their product eases joint pain)

TrionZ weak points
• Is sample size big enough?
• Results based on opinion only – no easily measurable data is collected
• Length of trial not long enough

The groups then feed back and ideas discussed. By the end of this part of the lesson you want the students to have clear guidelines of how to carry out a suitable experiment to test one of the claims. Record suggested guidelines so the class can refer back to them.

Students then use the experiment design sheet on pages 4 and 5 to design their own experiment which would result in more valid evidence. If you teach AQA, you might like to get your students to fill in the 'type of variable' column. They may need to be reminded about the different types of variable:
• Categoric – word labels
• Ordered – word labels that can be ranked, put into an order.
• Discrete – a numerical variable that takes only a finite number of variables
• Continuous – These can have any numerical value

Plenary (15 min)
Ask each group to describe their plan. Others in the class use the guidelines set out earlier to check that their evidence will be valid. After each group, the class raise their hands if they agree that the experiment will result in valid evidence.

Web links

News links

The Guardian

News story about IonX

Canterbury, New Zealand

Information from the makers on IonX shirts and how they work.

Bad Science

BadScience discussion on IonX shirts

TrionZ

An explanation of the 'science' of using negative ions to increase performance

Media links

YouTube

YouTube video commercial for IonX.
You can download videos from YouTube using sites like http://keepvid.com/

TrionZ

30-second commercial for TrionZ wristbands

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