Activity: Exploring Dyes - Levels 3 and 4
Achievement Objectives - Whāinga Paetae: Te Weu
3.1 (ii) Identify and compare permanent changes and temporary changes of selected substances. Te Marautanga o Aotearoa: (p.100-101) Ō Kawekawe, Ngā Āhutanga me ngā Panoni Matū. 1(i).
Achievement Objectives - Whāinga Paetae: Te Aka
4.1 (i) Classify materials by observing their physical and chemical properties such as acidity. Te Marautanga o Aotearoa: (p.100-101) Ō Kawekawe, Ngā Āhutanga me ngā Panoni Matū. 1(i)
Learning Outcome
I will be able to:
- make a prediction about mixing things
- mix substances and describe their changes
- identify changes that are permanent or temporary.
Success criteria
| Success criteria | Self-assessment | Peer assessment | Teacher assessment | ||||||
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| I can make predictions about mixing things. | |||||||||
| I can mix substances and describe their changes. | |||||||||
| I can identify changes that permanent or temporary. | |||||||||
Equipment
- Teabag
- Red cabbage
- Onions
- Baking soda
- Vinegar
- Iron supplement pill such as Ferrograd which contains Ferrous Sulfate
- Paper cup
- Kettle
- Microwave
- Teaspoons and knife
- White card
- Wax crayons
- Paint brushes
In this investigation you will be making dyes that are similar to those made using hīnau, tanekaha and raurekau. Instead you will be using a teabag, red cabbage and onions as in the table below.
| Harakeke dye | Dye made with kitchen ingredients |
|---|---|
| Hīnau mixed with mud rich in iron (sometimes known as paru) | Teabag with iron tablet added |
| Tanekaha mixed with wood ash | Red cabbage with baking soda added (Baking soda is a substance found in baking powder that makes gas when mixed with acid. The gas makes rewena rise.) |
| Raurekau | Onion skins |
All these dyes will involve a change of colour. Before you carry out your investigation, first make a prediction (making a guess about what might happen in the future).
| Dye made using: | What colour do you think it will make? |
|---|---|
| Teabag with iron tablet added | |
| Red cabbage with baking soda added | |
| Onion skins |
Making the dye
- Teabag dye: Add half a cup of boiling water to a teabag. Leave it to soak for a minute. Remove the teabag and add half a crushed iron supplement pill.
- Red cabbage dye: Boil a handful of chopped red cabbage in a cup of water for 2 minutes. Remove the cabbage leaves and add two teaspoons of baking soda.
- Onion dye: Boil a handful of skins from the outside of an onion in a cup of water for 2 minutes.
- What colour changes do you observe?
| Dye substance | Colour before | After addition of: | Colour after |
|---|---|---|---|
| Teabag | Iron tablet | ||
| Red cabbage | Baking soda | ||
| Onion skins | Hot water |
- Which of the dyes changed colour?
Using a fine wax crayon, draw a simple picture or pattern on a piece of white card. Paint in the sections of your picture using the dyes. Make sure there is some dye solution left over.
With the remaining dye, see if the colour of the solution will change after adding a tablespoon of vinegar or lemon juice.
| Dye | Colour before | After addition of: | |
|---|---|---|---|
| Teabag | Vinegar | ||
| Red cabbage | Vinegar | ||
| Onion skins | Vinegar |
- Which of the dyes changed colour after adding vinegar?
- What other changes besides colour did you notice after adding vinegar? Why do you think this happened?
- What do you think would happen to the colour of these dyes if you added baking soda?
Add a teaspoon of baking soda and see if you are right.
| Dye | Colour before | After addition of: | Colour after |
|---|---|---|---|
| Teabag | Baking soda | ||
| Red cabbage | Baking soda | ||
| Onion skins | Baking soda |
- What happened when you added baking soda to your solutions? Why do you think this happened?
Some of these changes are permanent and some are temporary. For example, if you mix egg white with water it is a temporary change. This is because you can easily remove the water by leaving the solution to dry. However, if you mix egg white with lemon juice or vinegar, the egg white turns white and cannot be changed back.
| Mixture | Permanent or temporary change |
|---|---|
| Teabag mixed with iron tablet | |
| Red cabbage mixed with baking soda | |
| Onion skins soaked in hot water |
- Why do think the above changes are temporary?
- Why do think the above changes are permanent?
We often mix things in the kitchen to make food. Sometimes this involves a permanent change and sometimes it is temporary.
- Make a list of permanent changes that happen in the kitchen when making food.
- Make a list of temporary changes that happen in the kitchen when making food.
For more activities on:
The solutions can be made in paper cups and can be heated in the microwave.