This morning I spotted a very simple experiment on the ScienceSparks twitter feed which was ideal for my early risers – http://www.science-sparks.com/2013/08/07/super-simple-surface-tension/
Super simple surface tension
What you need
• Cocktail sticks or matches
• A Bowl
• Washing up Liquid /Dish soap
• A large bowl
• Fill the bowl with water and let it settle for a few minutes.
• Carefully place the cocktail sticks on the top, if you can, try and get them to form a triangle.
• Add a drop of washing up liquid, and watch what happens.
The Science Part
This activity is a simple demonstration of surface tension. When you have a container full of water, the water molecules below the surface are pulled together equally in all directions, but those on top are pulled together more tightly, as they don’t have water molecules above them, this draws them together to form a kind of ‘skin’ which we call surface tension. When we added washing up liquid we disrupted the arrangement of the water molecules which decreased the surface tension inside the triangle of sticks.
Water molecules move from areas of low surface tension to high surface tension and so the sticks moved.
Don’t worry if that explanation seems like too much for your child. I don’t always explain the full scientific principles to my children, but watching and taking part in activities like these really does encourage children start to question why things happen, and the concepts we introduce will become start to make more sense to them as time goes on.
Now for our version of the experiment:
My son happily set about making a triangle.
He missed the target on the first try and the washing up liquid went to the side of the triangle pushing it to the side. My son was still impressed with the movement. We fetched a new bowl and tried again. This time the sticks were pushed apart,
“Wow it explodes!” he commented.
My son decided to develop the experiment by first trying ‘a complicated shape’ and then making a tower in the water out of the sticks.
My son was very satisfied by the change in the complicated shape as the liquid exploded some parts and pushed together others.
After building the water tower my son was interested in how the construction kept its shape despite being part submerged and simply laid together.
My son was so inspired that he wrote his school holiday diary immediately afterwards talking with excitement about his ‘exploding science experiment’!
Thank you Science Sparks, we enjoyed this one and I loved the fact that my son took the experiment in his own direction. I always find that the most successful activities are the ones that the children develop in their own ways.
With thanks to Science Sparks – http://www.science-sparks.com/