13 What is 'stuff' made of? 11-14 Working in groupsSelf assessmentPeer assessmentSharing objectives and criteriaQuestioningUsing feedbackUsing tests

This activity introduces atoms as a basic unit of matter. Students watch a simple demonstration and carry out a practical task in small groups to develop their thinking about this concept.

Learning objectives

Students will be able to describe that:

  • matter is made of atoms too small to be seen with the naked eye
  • atoms are the smallest parts of elements
  • an atom retains the property of the element
  • particles can move.

Sequence of activities

Introduce the topic and the purpose of the session, using a 1 kg bag of rice. Ask the students to guess how many grains of rice there are in the bag. After a few suggestions, give a clue – that there are about 1000 grains in 25 g. (1 million grains would be 25 kg, so 1 kg is 1 million / 25 = 40 000)
Say that rice grains are ‘small’ and ask, ‘how much smaller are atoms?’

An alternative introduction is to use the book Powers of Ten.

Give each student a copy of the worksheet It’s a small world!. Organise the students into pairs and support them with prompts as they complete the worksheet.
Allow about 15 minutes for the task.

In a plenary:

  • take their responses to question 1 (the number of hydrogen atoms in 1 cm is 1.35 x 106)
  • develop class lists of items that can be seen with the naked eye and those that cannot
  • introduce units for measuring small items, in particular the nanometre.

Introduce the next activity, to find out more about what atoms are like. Carry out the demonstration Atomic paper clips.

Allow about 5 minutes for the demonstration.

Give each student a copy of Atomic paper clips. Arrange the students into groups then circulate and support as groups:

  • discuss answers to the questions
  • reach agreement on the answers (this is important)
  • elect a spokesperson to feedback their answers to the class.

Allow about 15 minutes to complete the task.

In a plenary:

  • select groups to give their responses
  • review these responses using positive feedback and further questions
  • reinforce the idea that atoms are very small
  • reinforce the idea that atoms retain the property of the element, but the sub‑atomic particles do not.

Introduce the next activity, to find out more about how atoms behave.
Explain that they are going to add sugar and lemon juice to water to see how the taste changes. Give each student the worksheet Tasty particles and give each group a set of equipment. Supervise and support as groups:

  • carry out the practical task
  • agree on answers to the questions
  • elect a spokesperson to feedback answers to the class.

In a closing plenary:

  • ask the spokespersons for their responses
  • review these responses
  • reinforce the idea that particles (atoms) can move through water and that not all particles are the same.

Ask students to write down on the reverse of this worksheet what they have learned about atoms in the session.

Take in the sheets and give written feedback indicating the scientific correctness of their answers, together with support where further development of their thinking is needed.

Assessment for learning commentary

These tasks develop students’ thinking about the nature of matter. Ideas are considered through peer discussion and reflection, which should help make the ideas clearer. Plenary feedback enables the teacher to assess the extent of their understanding.

The group activity requires cooperation and care, as well as good discussion to answer questions.

Post-task reflection and subsequent teacher feedback supports students as they develop their ideas.

Resources

Stimuli

  • 1 kg bag of rice
  • Philip Morrison and Phyllis Morrison, The Office of Charles and Ray Eames, Powers of Ten. New York: Scientific American Library, 1994

Props

For each student

Download Word Download PDF It’s a small world!
Download Word Download PDF Atomic paper clips
Download Word Download PDF Tasty particles

Equipment

For each student

  • Eye protection.

For the atomic paper clips demonstration

  • A pile of paper clips – about 100 small ones
  • A sheet of fool’s gold or aluminium foil.

For each group

  • One glass or plastic drinking cup, with rings marked around 1/3 and 2/3 up the side of the cup
  • Drinking straws
  • Tap water
  • About 20 drops of lemon juice – enough to taste in water
  • About 10 g sugar (1‑2 teaspoons, there is no need to measure this accurately)
  • One dropping pipette.

Safety notes

It is the responsibility of the teacher to carry out an appropriate risk assessment.

Principal hazard

  • Drinking in a laboratory.

Answers

It’s a small world!

Small items we can see:
0.5‑3 mm pin head, sand grains, specks of dust, tiny flies / insects, holes /weaving in cloth
3‑5 mm insect larvae, creases in skin, shapes of fingerprints, crystals of salt and sugar, drops of liquid, eyelashes
Small items we can’t see:
0.1 mm details of salt crystal shapes, mites, details on a silicon chip
10‑100 µm cells, bacteria (variation depending on species)
0.3‑1 µm bacteria, viruses, DNA
1 nm molecules, atoms
1 pm atomic nuclei
0.1 fm the matter in a proton

Questions

  • About 0.5 mm
  • Our eyes are not sensitive enough
  • Atoms
  • They are very small.

Acknowledgements

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

Philip Morrison and Phyllis Morrison, The Office of Charles and Ray Eames, Powers of Ten. New York: Scientific American Library, 1994.