INVESTIGATING INK

INVESTIGATING INK Investigating Ink Organiser’s Card About the activity This activity is designed to get children thinking about how to identify different inks using chromatography. GATING INK Lady Felicity Feline’s prize winning Cocker Spaniel has been dog napped and a note has been sent asking for a ransom. Can the investigators work out which one of the four suspects wrote the note based on the type of ink used? Through this activity you will support your group to: • Experiment with different ink pens using chromatography • Design an experiment to help them identify the pen used to write a note • Share their conclusion and present evidence to support it. Kit list • Absorbent paper e.g. blotting paper, white filter paper, white coffee filters • Four pens (not biros) with black water-soluble ink inside, labelled with the suspects’ names – it’s better to have a set per group • Additional pen or black ink for the initial exploration – you must check that the colour separates • Ransom note (written using one of the pens prior to the activity). Don’t worry if it spreads a bit. • Beakers or pots • Scissors • Extra non-permanent marker pens in various colours • Plain paper for wanted posters

What to do 1. In advance prepare the ransom note according to the instructions in the kit list. 2. Introduce the activity by reading the news story together and examining the ransom note with the children. Show the children the suspects’ pens. 3. Give the children time to talk about ways of identifying which ink was used to write the ransom note. Give them a black pen or a blob of black ink and some white paper towel to explore the effect of water on ink. 4. Let the children explore the pens and the note. You will need to cut the ransom note into strips so that groups can each try out their tests. Things to think about Test the pens/ink prior to the activity by putting marks on pieces of blotting paper and dropping water on them. Some black inks will separate better than others. You need the criminal’s pen to produce a different pattern from the others. Cut more strips than you need to have some spares. You will probably need plenty of them! 5. Some children may need help to examine the different patterns and colours produced by each pen. 6. Give children time to talk about their evidence and decide who they think the culprit is. 7. Children can now create a wanted poster to help detectives track down the criminal they have identified. Encourage them to include all the evidence they have collected. 8. Encourage children to use the evidence from their experiment to justify their decision. Your ransom note must be written on absorbent paper e.g. blotting paper. Write a large note so there is enough for everyone. Your note could read: Lady Feline. If you want Colin returned safely, put £100,000 in a brown paper bag and leave it under the big oak tree by the town hall at 5.15 pm prompt tomorrow. Take it further Ink is made up of a mixture of different colours. Different inks will be made up of different colours even if they look the same. With water-soluble inks you can separate the colours from one another using water (chromatography). The colour from some other items such as food colouring, jelly beans and other sweets can be separated in the same way. Chromatography is used to separate and identify all sorts of substances in police work. Drugs can be identified in urine and blood samples, often with the aid of chromatography. ESTIGATING INK Keywords • Ink • Chromatography • Separation • Mixture • Absorbancy • Water-soluble Watch out! Use plastic beakers for this activity. Any spills should be cleaned up quickly to avoid accidents. Avoid using permanent marker pens British Science Association Registered Charity No. 212479 and SC039236