The science of separation – 1

Avneesh Shukla

If we examine closely, we can find that in our everyday life, we are always separating something or the other. Whether it is the tea we drink by filtering, or water through a filtration system, or separating particulates from the air by wearing a dust mask, separating compounds from the air or water with charcoal, centrifuging the water away from the clothes in a spin cycle of a washing machine, etc. – all these are common examples of separation. In this article I will be sharing my experiences of demonstrating this theme with the students of Government Upper Primary School (Class 6to 8), Uttarakashi.

seeds Before demonstrating this theme, I arranged the following materials and reading resources in the preparatory area:
• Pulses (chana, rajma, urad, etc.)
• Chalk, soil, and sand
• Water and oil
• Salt and sugar
• Beaker and funnel
• Transparent plastic bottle
• Straw
• Naphthalene ball and Cotton
• Glass rod
• Magnets
• Nails
• Sprit and sprit lamp
• Wire gauge and tripod stand
• Simple and what-man filter paper

I divided students into two groups and gave them a mixture of three pulses (chana, rajma, urad, etc.) and asked them to do anything they wanted with the mixture. After thinking and observing for a minute, one group separated the pulses into different sets – chana, rajma, and urad. The second group was not able to do anything. However after observation, the second group too separated the pulses into three sets. Then, I mixed soil and chalk powder and asked the groups to separate them. The two groups separated the bigger sized chalk (calcium carbonate) and some small sized stone particles but they were unable to separate the soil and chalk powder.

After this activity I asked them what they did. They responded saying:
“Since the size of the pulses were different, we were able to separate them, but soil and chalk powder were different. They were mixed together or the size was smaller that’s why we were unable to separate them.”

The author is with the Azim Premji Foundation. He can be reached at

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