42 Do crystals have special properties? 14-16 Working in groupsSelf assessmentPeer assessmentSharing objectives and criteriaQuestioningUsing feedbackUsing tests

This discussion activity uses genuine ideas about crystal properties to prompt students’ reasoning about scientific evidence. It should follow on from previous work on crystals.

Learning objectives

Students will be able to:

  • distinguish between hearsay and scientific evidence
  • debate an issue based on evidence
  • plan an investigation to test a contentious issue.

Sequence of activities

Introduce the idea that some people think crystals have ‘special properties’. Ask if students know of any.

Display pictures from crystal therapy websites to support this.

Explain to the students that they are going to look at people’s ideas about crystals, discuss if these are true or not and plan an investigation that would determine if crystals do have special properties.

Give each student a copy of the Background information sheet and the worksheet Do crystals have special properties?

Organise students into groups of three or four. Circulate and support as groups:

  • read the background information
  • answer the questions
  • select a spokesperson to feedback answers to the class.

In a short plenary:

  • invite some of the groups to share their responses to the questions.

Not all groups need report back but, before proceeding to the next task, review sufficient answers so the background is agreed and common to all.

Explain that the next task is to plan an investigation to answer the question ‘Do crystals have special properties?’

Indicate that groups are expected to present their plans and review each other’s work.

Supply each group with presentation equipment.

Internet search facilities could also be used to help collect material.

Circulate and support as each group:

  • plans an investigation to collect scientific evidence that would answer the discussion question
  • creates a presentation of their plan
  • elects a spokesperson to present the plan.

In a plenary:

  • arrange for each group to present the results of their investigation and their plan
  • encourage students to listen to the plans and comment constructively on the approaches used
  • review and refute the evidence for crystal ‘special’ properties
  • check for understanding that crystals do not have special properties.

Ask students to write a statement that answers the discussion question, includes details of their planned investigation and indicates their own understanding of the issue.

Take in the statements and give feedback that reflects the quality of the investigation and the extent to which the answer uses scientific ideas.

Assessment for learning commentary

The presentation of investigation plans permits peer assessment. Criteria for making the assessment may be agreed with the class in advance; features such as fair testing, use of variables, review of data, evaluation and reliability may be included.

Teacher feedback on the written task results from an assessment of how well the student understands the scientific aspects of this topic as well as the quality of the investigation planned.

Resources

Stimulus

For crystal therapy illustrations

Props

For each student

Download Word Download PDF Background information sheet
Download Word Download PDF Do crystals have special properties?

For each group

  • Access to materials for making a presentation, such as large sheets of paper and marker pens, OHTs and OHT pens, networked computer and/or CD-ROM writing facilities
  • Access to internet search facilities (optional).

Answers

Why do people think crystals have special powers?
People do not think scientifically. They may be attracted to the rarity, shape and colour of the crystals. Anecdotes about possible “healing” experiences may influence people’s thinking about crystal powers.

What is the evidence for crystals having these powers?
Historical traditions, anecdotes

Statement Correct science
Quartz is a powerful energy source. Crystals are not energy sources.
Amethyst enhances psychic abilities. A crystal cannot enhance psychic abilities.
Rose quartz is the love stone which adds positive energy. A crystal cannot add positive energy.
A crystal can hold a memory. A crystal cannot hold a memory like a brain.
Dedicate a stone to healing and put it in your pocket. As you touch it during the day it may help stimulate self-healing. Touching a crystal cannot heal an injury.

Acknowledgements

V. Kind, Contemporary chemistry for schools and colleges. London: Royal Society of Chemistry, 2004.