Red Cabbage Chemistry

Type of resource: Video

Web address https://youtu.be/PYYowXOEZZE

Language: English

Description

Experiment using red cabbage as a pH indicator

Scientific concept introduced

Identifying acids/bases using a pH indicator

Creative and critical thinking

Critical Thinking:
– Prediction
– Inferencing
– Explanation

Creative Thinking:
– Desicion Making
– Curiosity

Mathematical reasoning

– Measuring
– Counting

Scientific thinking

– Questioning
– Observing
– Predicting
– Making
– Testing
– Classifying
– Drawing conclusions

Learning how to learn

– Active listening
– Following guidelines
– Self-directed learning
– Engagement in learning
– Turn taking in groups

Additional

– Oral language – listening and following instructions
– Literacy – vocabulary development
– Cooking skills of pouring, mixing and measuring
– Pre-reading skills – sequencing
– Collaborative skills of sharing and turn taking

https://www.youtube.com/embed/PYYowXOEZZE?feature=oembed

Red Cabbage Chemistry

Overall aims

● to enable pupils to explore what happens when an acid or a base is added to a pH indicator
● to enable pupils to identify characteristics of cabbage
● to develop pupils’ skills in listening and following instructions
● to develop pupils’ cooking skills of pouring, straining, mixing and measuring
● to develop pupils’ skills in observing and predicting
● to develop pupils’ skills in counting
● to develop pupils’ skills in turn-taking
● to develop pupils’ skills in measuring (capacity)

Vocabulary – keywords should be understood

Red cabbage, indicator, acid, base, vinegar, baking soda, strain, purple, green, blue, red

Expected learning outcomes (operational aims)

The child will be enabled to:
– follow instructions for the experiment
– count cabbage leaves
– practice the skill of straining a liquid
– make observations and predictions during the experiment
– identify vinegar as an acid and baking soda as a base
– work together in small groups

STEM skills – to which the learning unit is related to

CORE STEM SKILLS

● Asking questions
● Observing
● Predicting
● Explaining
● Inferencing
● Making
● Testing
● Classifying
● Decision making
● Drawing conclusions
● Curiosity

● Counting
● Measuring

ADDITIONAL SKILLS

● Health and safety in the kitchen
● Active listening
● Following guidelines
● Self-directed learning
● Engagement in learning
● Turn taking
● Oral language
● Literacy – vocabulary development and pre-reading skills of sequencing
● Cooking skills of pouring, straining, mixing and measuring
● Collaborative skills

Teaching methodologies/activity outline

Teacher Note: This experiment requires adult supervision

Introduction:
1. Write the word ‘cabbage’ on the board, eliciting what pupils know, for example, it’s a vegetable, it has big thick leaves, it grows in the ground; it can be green or red.
2. Inform pupils that today they’re going to be using red cabbage to make what scientists call a pH indicator, to do an experiment. A pH indicator changes colour when it comes in to contact with an acid or a base and this colour change tells us if something is an acid or a base. Acids and bases can be found all around the home – we’re going to test vinegar and baking soda to find out whether they’re acids or bases.

Activity:
(Ask pupils to work in groups of 5 or 6, reminding them to take turns).

Materials: (per group)
– 4 red cabbage leaves
– 4 cups of water
– Blender
– Strainer
– A large jug (enough to hold the 4 cups of water)
– 3 tall glasses
– 2 teaspoons (1 for vinegar; 1 for the baking soda)

Instructions:
(Each group will need to be carefully supervised by an adult)
1. Ask groups, with pupils taking turns, to pour 4 cups of water into the blender container.

2. Then ask pupils to add the 4 cabbage leaves to the container, putting the lid on. Ask pupils why it’s important to put the lid on for blending, eliciting that the mixture would spread everywhere.
3. Ask the supervising adult to connect the container to the blender machine and to blend until smooth – keep watching to make sure it’s blended well.
Note – Explain to pupils that a blender has blades which move very fast to blend whatever it is mixing, so it’s important that the adult does this job.

4. Show pupils the strainer informing them that this is a kitchen utensil. Ask them what they think it’s for – a strainer is sometimes used to sift ingredients, like sifting flour in baking but mostly a strainer is used to strain liquid away from other ingredients, which is what we do in this experiment.

5. Remove the container from the machine and ask pupils to use the strainer to strain the liquid into the large measuring jug. This liquid – the cabbage juice – is your pH indicator.

6. Ask pupils to share out the pH indicator, pouring it equally into all three glasses. What colour is the liquid? (a purple colour)

7. Ask pupils to add a teaspoon of vinegar to the first glass and to stir – ask the pupils to observe what happens. The liquid changes to a red colour.

– This tells us that vinegar is what we call an acid because acids turn a reddish colour when mixed with the pH indicator.

– Tell pupils that lemon juice is also an acid. Ask them what they think would happen if it was added to the cabbage juice. Again, the liquid changes to a red colour.

8. Next ask pupils to add a teaspoon of baking soda to the second glass and to stir – ask the pupils to observe what happens. The liquid changes to a blue-green colour.

– This tells us that baking soda is what we call a base because bases turn a blue-green colour when mixed with the pH indicator.

– Tell pupils that washing powder is also a base. Ask them what they think would happen if it was added to the cabbage juice. Again, the liquid changes to a blue-green colour.

9. The third glass with the pH indicator is what we call a neutral solution, an example of a neutral substance is water.

Conclusion:

Ask pupils to draw the results of the experiment, for example, drawing the 3 glasses and labelling the solutions – acid, neutral and base; and showing the different colour changes.

Assessment of learning

Pupil observation sheet

Equipment and materials to be used in learning unit (tools, ingredients etc)

Materials: (per group)
4 red cabbage leaves
4 cups of water
Blender
Strainer
A large jug (enough to hold the 4 cups of water)
3 tall glasses
2 teaspoons (1 for vinegar; 1 for the baking soda)