SURPRISING STAINS

SURPRISING STAINS Surprising Stains Organiser’s Card SURPRISING STAINS About the activity This activity is designed to get children thinking about chemistry. Cosmic and Gem have been picking and eating blackberries and managed to get juice on their white tee shirts. Cosmic puts soap on his, Gem puts lemon juice on hers. Both of the stains changed colour - can the children work out why? Through this activity you will support your group to: • Investigate what caused the colour changes. • Explore different plant materials (food) that change colour. • Group chemicals by colour change and make a chart. Kit list • Blackberries - you do not need a lot of juice (you could use ripe blackcurrants instead) • Saucers or small containers • Spoons • Lemon juice (bottled is fine) • Liquid soap • A selection from lime juice, vinegar, fizzy drinks, apple juice, white grape juice, orange juice, crushed rhubarb, cream of tartar, yoghurt etc. (optional) • A selection from baking soda, mild washing powder, indigestion tablets, milk of magnesia, toothpaste, window cleaner (with ammonia) etc. (optional) • Other dark coloured plants - see the ACTIVITY CARD. What to do 1. Read the ACTIVITY CARD to familiarise yourself with the activity. 2. Check the Kit list and ensure you have the correct resources. 3. Set the scene by discussing the story with the children. 5. Encourage children to talk together to develop their own ideas. 6. Encourage children to follow Frank’s ideas and then to explore their own ideas. 7. Encourage the children to make their own records. This might include creating a poster or chart. 4. Help the children to identify what the problem is.

Things to think about Many of the plants listed in the ACTVITY CARD will change colour. Many red or purple plants will work, but red cabbage is particularly effective. The slightly smelly, but strongly coloured, liquid gives a broad range of colours when various substances are added. Extracting the colour is best done by boiling the cabbage. Encourage children to compare several plants. Keywords • Stains • Colour • Plants • Berries • Acid • Alkali • Chemistry. Watch out! More colour can be extracted from plant material if it is heated. Only allow children to use hot water under supervision. Using warm water helps reduce the safety risks. Do not let children use any substances in the kitchen that may be hazardous such as bleach, washing soda, dishwasher detergent and powerful cleaners. Do not taste anything in this activity. British Science Association Registered Charity No. 212479 and SC039236