Understanding the World: Chain reaction

Jenni Clarke, author and consultant, France
Wednesday, October 9, 2019

The first in this ‘little scientist’ series explores the nature of chemistry and outlines some simple but exciting experiments, which will ignite children's curiosity and encourage them to make predictions based on what they see.

In its simplest form chemistry is the ‘what will happen if I put these two substances together?’ branch of science.

Young children are naturally experimenting with chemistry when they mix water into sand or soil, add bubble bath to water, try chocolate spread on cucumber and mix colours together. Channelling their curiosity with some fun activities, modelling scientific language and methodology will promote thinking skills and problem solving as well as help children to understand the world around them.

Playing and exploring

  • Children test their curiosity as they experiment with open ended resources.
  • They have a go at identifying similarities and differences in the substances they are playing with.
  • As they put on their lab coat to become a chemist, they experience a real-world job through role-play.

Set up an area as a chemistry lab with lab coats, goggles and gloves. Add a set of glass jam jars, a jug of water, long handled spoons, labels and containers with substances from the kitchen, such as flour, corn flour, sugar, oil, jam, marmite. Observe how the children interact with the area, support their experimentation by using correct vocabulary and encourage them to add substances to the water. Discus what happens and use terms such as stir, dissolve and separate. Encourage children to make slime by mixing corn flour and water.

Set up a new experiment using fairy cake tins, bicarbonate of soda, a spoon, white vinegar and a pipette. Children should now be used the safety equipment and understand the nature of experimentation, so observe and listen to their chatter as they see what happens when the two substances mix. Encourage them to try adding more bicarbonate of soda or more white vinegar.

To help them understand what is happening, dissolve the bicarbonate of soda in a jar of water, add some grains of rice and then drop in some vinegar. Talk about what they see – how the rice is catching the gas bubbles which are released by the two substances mixing together, how the bubbles float the rice to the surface and the gas is released into the air so the rice sinks. This is mesmerising to watch and can be repeated many times.

Dinosaur land

Set up a tray with a hollow volcano, dinosaur terrain and dinosaurs. Hang a challenge above the table. ‘Can you make the volcano erupt?’ Children who haven't visited the chemistry lab may fill the volcano with tissue paper or beads, but once they've seen an eruption with red flowing lava bubbles they may wish to know how and why. It may entice them to try some experiments for themselves.

Active learning

  • Extending the experiments increase the children focus and fascination as they notice the changes when a new element is added.
  • There are opportunities for being proud and excited about results but also the process as attention to detail is needed.
  • Using simple substances found in a kitchen gives children the opportunity to make connections between the setting and home.

To extend the dissolving experiment, ask questions such as ‘what if we used warm water, would it make a difference?’ ‘Can you find a way to record what happens?’ ‘Does it make a difference how fast the water is stirred? and ‘What about shaking the bottle?’

Children will have discovered that oil and water remain separate, so build on this knowledge by adding food colouring using pipettes. Watch as they observe the food colouring sitting on the oil, then slipping through to make patterns in the water below. If they ask more questions about oil and water you can talk about how oil is lighter or less dense than water and that's why it floats to the top. This may lead to some floating and sinking experiments in the water tray.

To keep their interest in the bicarbonate of soda and vinegar experiment, add food colouring with pipettes or in small dropper bottles. The colouring could be placed under the bicarbonate so it is a surprise when they add the vinegar. Alternatively, the bicarbonate can be spread onto a tray, food colouring dropped on and then vinegar put on top of the colour. Support their findings by modelling correct language and by asking open ended questions. There is the added bonus of talking about colours mixing and changing too.

Creating and thinking critically

  • Children have the opportunity to predict, test and then review what has happened as they become more systematic in their approach to the chemistry experiments.
  • They observe what happens and begin to answer the ‘why’ question of science.
  • While playing they have the opportunity to find out more about the wider role of a scientist and the importance of answering questions through experimentation.

Develop the oil and water experiment by using bottles or bags to mix the oil and water, shaking or turning them to see how long it takes for the water and oil to separate again. Discuss ways of recording what happens, of measuring the time it takes as well as challenging children to think of other ways to make interesting patterns in bottles for younger children to play with (ensure the bottles are firmly sealed). Some children may be interested in understanding something is denser when it's molecules are closer together.

Add a forth ingredient – washing up liquid – to the bicarbonate and vinegar experiment. Ask the children to predict what might happen. They have seen bubbles with the rice and they will all know about washing up bubbles so they may guess correctly. Encourage children to find different shaped containers to try the exploding vinegar experiment. Is it different in a tall thin bottle, what about on a tray? Ask them to think of ways to record what they are doing and discovering – perhaps with a camera or by making a booklet or a wall display.

Set up a new experiment with slices of different citrus fruit in a cake baking tray. Ask children to taste some of the juices and to taste the vinegar used in the other experiment. What do they notice? If they do not make the connection between the acidic nature of vinegar and the fruit then add a pot of bicarbonate and ask the children what they think might happen if you put some bicarbonate on the fruit. Let them test one and then predict which fruit will create the most bubbles. Will the bubbles be the same colour as the fruit? What will happen to the fruit scent? Talk about their predictions and the results.

EYFS Learning Goals

The experiments involving the use of food colouring also support Expressive Arts and Design. The patterns in the oil can be captured on camera and used in a display or to inspire paintings. Bicarbonate on a tray with food colouring and vinegar not only involves colour mixing but the patterns and colours can be captured by a camera or on watercolour paper – like a print. This gives the children the opportunity to demonstrate the following learning goals: ‘They safely use and explore a variety of materials, tools and techniques, experimenting with colour… Selects appropriate resources and adapts work where necessary. Children use what they have learnt about media and materials in original ways, thinking about uses and purposes.’

Key learning points

  • Children learn to patiently observe changes in liquids and materials and grasp the idea of ‘an experiment’
  • They develop vocabulary to express what they see
  • They enjoy the anticipation of discovering what happens next

Key words:

  • Experiment, pipette, substance, predict, result, laboratory

Useful resources

  • Lab coats, safety goggles, gloves, name badges
  • Vinegar, bicarbonate of soda, food colouring
  • Glass jars, pipettes, funnels
  • Measuring jugs, spoons
  • Substances from the kitchen – dried rice, flour, sugar, salt, corn flour etc
  • Citrus fruits
  • Oil, water and food colouring, washing up liquid
  • Aim to recycle foods and substances used for these experiments, and keep waste to a minimum

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