Help students consolidate their ideas about atoms and atomic structure, working in pairs to identify key concepts, using this lesson plan for 16–18 year olds

In this activity, students review ideas connected with the structure of atoms using a set of ‘similar and different’ cards, featuring key phrases relevant to the topic. Students work in pairs to identify the phrases from the description of the similarities and differences given by another pair of students.

It is a tool to review and consolidate learning on the topic.

Learning objectives

Students will be able to:

  • Understand ideas connected with the structure of atoms.

Sequence of activities


  1. Project an image of the emission spectrum of hydrogen. Invite students to comment on what they are looking at.
  2. Ask students to work in pairs to list what they think they should know about the structure of atoms and related topics.
  3. Bring the students together and compile a list from their suggestions.
  4. Ensure that the list includes topics relevant to the specification being followed. Examples are: isotopes, atoms and ions, ionising radiation, mass spectra, atomic emission and absorption spectra, historical development of ideas about the atom.
  5. Confirm that the objective of the session is to check and clarify their understanding of the topics they have identified.

Activity: example and set-up

  1. Use an example to illustrate to the students what they will be doing.
  2. Ask the students, as a whole group, to suggest similarities and differences between a chlorine atom and a chlorine molecule, without actually using the name.
    • Similarities: both contain the same atoms, atoms in both contain 17 protons, both are neutral.
    • Differences: one contains twice as many protons, neutrons and electrons as the other, one contains an unpaired electron, one is much more reactive than the other, one is described as a free radical.
  3. Explain that the students will have to identify two phrases from a description of their similarities and differences.

Activity: stage 1

  1. Arrange students into pairs. Give each pair a numbered ’Similar and different’ card.
  2. Task each pair to think about the similarities and differences between the two phrases on the card.

Activity: stage 2

Organise the pairs so that:

  1. They join up with another pair of students that has a different numbered card.
  2. Pair A describes the similarities and differences between the phrases on their card, without saying the exact words on the card.
  3. Pair B has to guess the phrases.
  4. When pair B has identified the phrases, the roles are reversed (pair B helps pair A to guess what is on pair B’s card).
  5. When pair A is successful, the two pairs exchange cards.
  6. They now focus on the similarities and differences of the phrases on the exchanged card.
  7. They each join with a new pair of students who have a card with a number different from the ones they have met so far.

Allow the process to repeat until each pair has identified the features on all cards.


Bring the students together in a plenary. Ask for them to show the extent of their understanding by raising a number of fingers on one hand:

  • Five fingers for very well.
  • Fist for not at all.

Check for understanding about isotopes, atoms and ions, ionising radiation, mass spectra, atomic emission and absorption spectra, historical development of ideas about the atom.

Before finishing

As a result of the finger test, select one or two topics which are proving particularly challenging for some students. Arrange the students in groups of four in which two have indicated that they have a good understanding of one of the topics and two are less confident about their understanding. Provide time for group discussion (using the cards as prompts) so that students who are confident about their understanding of a topic help those who are less confident.


By questioning themselves and pooling their ideas at the start of the session, students realise the relevance of the learning objective.

Throughout the activities the students reassess any shortcomings in their understanding since they are required to clearly articulate the essential features of atomic structure. This process may include being challenged by their partner or by other pairs of students.

After the overt self assessment towards the end of the session, students help others or are themselves helped which all leads to confidence in their understanding of the topic.