Help your students consolidate their ideas about acids and alkalis using this lesson plan and set of downloadable activities 

Key words that students have met during their work on acids and alkalis are linked together by appropriate phrases on a concept map. The map is used as a probe to help students structure their discussion about acids and alkalis. A number of variations of the concept map are included so that teachers can choose the approach they feel is appropriate, depending on the stage and support needs of their learners.

This lesson plan is the first part of a two-part series. For the second lesson, see Acids and alkalis: a concept cartoon.

Learning objectives

Students will be able to:

  1. Make connections between key ideas to do with acids and alkalis.
  2. Explain how these key ideas are connected.

Sequence of activities


  1. Show a beaker half full of dilute hydrochloric acid labelled ‘STOMACH ACID’.
  2. Add universal indicator to the acid solution.
  3. Add an antacid tablet to the solution in the beaker so that the colour of the indicator changes.
  4. Ask students to suggest words they might need to use to explain what has happened in the beaker and compile a list on the board or OHP.
  5. Describe the learning objectives for the session.

Health, safety and technical notes

Read our standard health and safety guidance.

Concept mapping: stage 1

  1. Arrange the students in pairs, and give one copy of ‘Concept map 1’ to each pair.
  2. Give one copy of ‘Linking phrases sheet 1’ to each student.
  3. Explain that the task is to link together the words on the concept map.
  4. Circulate and support with prompts while students:
    • Work in pairs.
    • Decide on (or select) the correct phrase to link the boxes.
    • Complete the table on the ‘Linking phrases sheet’.
    • Put in two more boxes of their own and devise the phrases to add to their table.

Concept mapping: stage 2

  1. Ask each pair of students to join with another pair to form a group of four.
  2. Circulate and support with prompts while students:
    • Work as a group.
    • Compare their initial phrases and discuss any differences.
    • Fill in the column on the right of the ’Linking phrases sheet’ to indicate how well they think they understand the links (using a key such as 3, 2, or 1 star(s) or other symbols for ’Understand’, ’Not sure’ or ‘Don’t understand’).
    • Select a spokesperson.


In a plenary, ask:

  • Each spokesperson to describe the phrases the group has used to connect key words.
  • Other groups to comment on the phrases or to suggest alternatives to link these words.
  • Each spokesperson to identify those links which were difficult.

Allow time for students to review their work in the light of the whole-class discussion.

Concept mapping: stage 3

  1. Provide each student with a copy of ‘Concept map 3’.
  2. Circulate and support with prompts while students:
    • Work individually.
    • Identify which links they found most difficult and how they are going to work on these points.
    • Write this assessment on the back of their ’Linking phrases sheet’.
    • Hand in the sheet.


Give feedback to each individual. Acknowledge achievement and write comments that will lead the student towards their next steps.

Activity notes

  • ’Concept map 1’ has arrows already inserted between key words; students write in appropriate linking phrases on ’Linking phrases sheet 1’.
  • For a more demanding task, use ’Concept map 2’ and ’Linking phrases sheet 2’.
  • For a less demanding task, photocopy ’Concept map 1’ to A3 size and photocopy and cut out the individual cards on the ’Connecting phrase cards’ sheet. Students can use these on their concept map before completing the table on ’Linking phrases sheet 1’.


The initial demonstration vividly illustrates the key ideas. During the group work, the students can articulate their ideas about acids and alkalis and are then more likely to identify what they are less confident about. The teacher gains a clear picture, in the plenary, of which ideas the whole class finds most demanding. Providing a completed concept map will help students to recognise the standards they are aiming for.

Notes for Primary teachers

If you teach primary science, see the information below to find out how to use this resource:

Skill development

Children will develop their working scientifically skills by:

  • Using appropriate scientific language and ideas to explain, evaluate and communicate their methods and findings.

Learning outcomes

Children will:

  • Draw connections between different key words relating to the topic of acids and alkalis.

Concepts supported

Children will learn:

  • That substances can be classified as acidic, alkaline or neutral, through the use of everyday examples.
  • That the human stomach uses acid to aid digestion, which can be neutralised using alkalis and other antacids. 

Suggested activity use

You could use this activity as a stimulus and as a way to introduce key words related to the subject of acids and alkalis, linking this to the topic of the human digestive system. You could also use it to introduce flow charts/classification keys. If you choose to use hydrochloric acid then the initial demonstration needs to be carried out by an adult. Alternatively, children could carry out this activity using lemon juice or white vinegar.

This resource provides great opportunities for assessment, as it enables children to articulate their ideas about acids and alkalis and identify what they are less confident about.

Practical considerations

Some of the language used in the resource are beyond primary level, so children may need support in understanding the terms.

Hydrochloric acid may not be available in primary schools – alternatives such as lemon juice or white vinegar can be used.