Cohesion and Surface Tension {Science Sunday}

This week we talked about molecules…and cohesion…and surface tension. Water, soap, and newspaper were involved. Did I mention water and a squeezable bottle of dish soap?

And Mommy only wanted to bang her head on the table once.

The question to find the answer to: What will happen when two ‘men’ made out of newspaper are put into water ~ one in soapy water and one in plain water.

Items we used for the experiment:

• 2 plates
• water
• dish soap
• newspaper men

The kids made predictions about what would happen to the little man dropped into the soapy water ~ would he sink? sink faster than the man in plain water? sink slower? same speed? All the kids thought he would sink faster ~ and they were right!

We put water on both plates and added dish soap to one of the plates. We gently put the newspaper guys on each plate and watched to see which guy decided to sink first.

 

After the experiment was finished, each of the kids answered several questions about what had happened and the why behind it and then drew a picture illustrating what the results were. This has really been fun to see their interpretation of the experiment.

The Nutshell Reason…

The dish soap reduces the surface tension of the water. The water molecules, instead of sticking together, attach themselves to the other material in the water {dish soap}. When the newspaper is put on to the water, the water immediately makes it wet and it sinks. The paper put in the plain water will take longer to get wet.

Resource: How to Do Science Experiments with Children is available from Amazon and you can also check it out {and do some of the experiments} using Google Docs! The experiments use easy-to-find objects and also include record sheets for kids to fill out with their predictions and experiment results. Each experiment also includes teaching tips and explanations…which are rather handy! :)

Don't forget to check out some other great science ideas at Science Sunday hosted by Ticia at Adventures in Mommydom.