Energiser
- Show Video Clip 1: Sense of Taste & Smell - Our Tongue & Nose [1:54 min.].
Introduction
- Greet the learners.
- Tell the learners that they will deal with different chemical substances at home and at school during their Natural Sciences periods.
- Let them mention which cleaning products are on the market and the purpose of each one. Possible answers [Washing powder, soap, bleach, brasso, Handy Andy, dishwasher; shampoo, conditioner, polish, etc.].
Teacher Input 1
- Establish what the learners know by asking the following questions:
- How is the water in the swimming pools being kept clean?
- What household liquid can we use to unblock drains?
- Why do we squeeze lemon juice over bananas when we make fruit salad?
- Tell them that they will be learning more about the tastes of different substances in the video and presentation that will follow.
- Show Video Clip 2 [0:38 min.].
Learner Activity 1
- Learners respond to the questions that were asked.
- They give examples of various cleaning products that are presently available as well as each ones’ purpose.
Teacher Input 2
- Ask the learners to explain the function of their tongues.
- Inform them that the substances in the food have a reaction on our tongues’ taste buds and bring the following under their attention:
- Our sweet taste buds will send a message to our brains through our nerves and then the taste of the food will be interpreted by our brains.
- This will also happen to our bitter, sour and salty taste buds.
- Our sense of smell also contributes to our interpretation of different flavours.
- Stress that there is no specific area on our tongues for any particular taste.
- Scientists had a hypothesis that there were specific areas for each taste bud on our tongues, but it has been disproven. [Note the sketch in presentation 1].
- There is also a 5th taste, umami that is present in different Asian dishes.
- Present an overview of the different tastes of substances by using Presentation 1: Tastes of substances.
- Inform the learners that they will first report back on the presentation and then complete an activity in which they have to taste certain substances and identify it according to its taste.
- Bring it under the learners’ attention that certain substances are not safe to taste and they should avoid tasting unknown substances.
Learner Activity 2
- Groups discuss the content of the presentation briefly for 5 minutes and report back.
- Complete Worksheet A: Acids, bases and neutrals.
- Teacher to use Worksheet A: Memorandum to mark the learners’ work.
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