Sometimes science can seem a little bit magical, so why not amaze your children with this nifty trick before teaching them the science behind it.
Let your kids' jaws drop to the floor as you make a paper clip float on water and discover the laws of surface tension with this easy and exciting science experiment. Your floating paper clip could inspire a whirlwind of learning and exploration into the wonderful world of science.
You will need:
A paperclip (or a few)
A bowl of water
A cotton bud or a pencil with a rubber on the end
Optional: baby powder or laundry detergent
Setting Up Your Experiment
To really WOW your kids, you should get them to try and make their own paperclips float first. They will drop them into the water and see them sink to the bottom rendering it impossible for you to do. Then you can shock them with the simple use of your kitchen roll to help you out:
1. Fill your bowl about 3/4 full of water
2. Next, place a small square of tissue paper on the surface of the water, trying to make sure that you place it down evenly do the tissue itself doesn't sink.
3. Once your tissue is floating, place your paper clip on the tissue trying to touch the water or the tissue with your fingers.
4. Then if your paperclip is sitting happily on top of your kitchen roll (it may take a couple of tries) then you can use your cotton bud or the rubber end of the pencil to push the piece of tissue away from underneath the paperclip and then you should have your very own floating paper clip!
The Sciency Bit
So how does it work? Well, this all comes down to the idea of surface tension. Water molecules are packed very tightly together, and being a liquid the molecules are highly adaptable to shape. Surface tension is the idea of a 'skin' being created on the surface of the water where the molecules pack tightly together to hold what is floating on top of it, so given the right push, the skin of the water can pack tightly enough to hold up the weight of the paper clip; giving it the illusion of floating.
Add Some More Fun
There are lots of things you can do to make this more of a science experiment and engage your children with scientific thinking.
1. Try adding some detergent or baby powder to your water - does your paperclip sink? and if so, why? The detergent may interfere with the surface tension of the water by acting as a 'surfactant' so your paperclip may not float as easily.
2. What about if you change the shape of the paper clip?
3. Float paper instead of tissue and see if that changes the experiment.
4. How many paper clips can the surface tension hold?
Recording Your Results
It is always fun to record the results of your experiments and helps children learn about the importance of theories and the experiments that prove them. Why not create a table of all the different ways you try to float the paperclip so that you can compare your results at the end?