Acid-base indicators

• Determine what the learners know about litmus paper.
• Explain to the learners that litmus paper is used to test whether certain substances are acids or bases.
• Also inform them that both the red and blue litmus paper must be used when a substance is tested.

• Find out from your learners if they like cooking/ gardening/ sowing/ etc.
• Tell them that the next video clip will guide them to make their own litmus
• Choose one of the following video clips that will be suitable for your learners:

Video Clip 10: Making your own litmus paper at home. [4:36 min.].

Video Clip 11:  Make your own litmus paper.  [2:47 min.].

• Tell the learners that they have gained a lot of knowledge about litmus paper, acids, bases and neutrals.
• Mention that other indicators can also be used, especially in laboratories, e.g. Bromothymol blue, Methyl orange and a Universal Indicator.
• Present an overview of acid base indicators by using Presentation 3: Acid base Indicators.

• Complete Worksheet C: Acid and base indicators.
• Teacher to use Worksheet C: Memorandum to mark the learners’ work.
• Complete Worksheet D: The learners work in groups and they must test the different household substances within a specified time in the classroom. Correct recordings must be written in the appropriate columns.
• Teacher to use Worksheet D: Memorandum to mark the learners’ work.

• Learners complete QUIZ 1.

• Teacher to use QUIZ 1: Memorandum to mark the learners’ work.