Page 34 - FOUNDATIONS FOR LIFE; EXPLORING GOD’S UNIVERSE

CHROMATOGRAPHY

Truth to Teach (Source)

 Coloured objects are able to reflect some of the colours in the light that falls on them
because they contain certain substances called pigments.

 Pigments can be separated; this is called chromatography.

Way to Work (Means)

Equipment: Dyes, felt-tip pens or food colourings, white absorbent paper or coffee filters or
kitchen roll, trays of water.

1. Review the previous lessons on light.

2. Write the words ‘pigment’ and ‘chromatography’ on the board to see if anyone knows the
meanings of them. (pigment = colouring; chromatography = different pigments travel at
different speeds up certain papers to show separate bands of colour.)

3. Divide the children into groups with the above equipment to conduct experiments.

Experiment: a) Cut absorbent paper into strips about 2 cm by 30 cm.
b) Put a drop of ink or dye about 4 cm from the end of the paper.
c) Hang the paper strips with string and pegs so that the ends with the
drips of ink or dye just dip into the water.
d) Remove each strip of paper from the water when the colour is nearly at
the top.
e) Allow the paper to dry then examine the colours.
f) Repeat using different materials – paper and inks, dyes, etc.

4. Gather to share results. Discuss whether the children had conducted fair tests. Give the
children time to write up their experiments.

Learning for Life (Fulfilment)

The children will have enjoyed conducting these experiments and will have seen how the different
pigments travel at different speeds up certain papers to show separate bands of colour. They will

appreciate that pigments are responsible for the colours we see in certain objects as light falls upon
them.

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