A simple experiment out of 50 Science things to make and do (by Usborne Activities) that we tried recently was a surface tension experiment. I have seen similar experiments elsewhere on the internet and in books, but found the scientific explanation in this book to be the most clear for my 3 and 5 year olds.
We’re really enjoying the experiments in this book and it has spurred Cutie Pie on to suggest experiments of his own!
Materials needed:
bowl
water
milk
toothpick
pepper
food coloring
First fill a bowl half way with water and sprinkle a little pepper on the surface.
Then dip a toothpick into your dishwashing liquid. Touch the middle of the water with just the tip of the toothpick. What happens to the pepper? Cutie Pie hypothesized the pepper would sink.
Next, fill a bowl half way with milk and add a few drops of food coloring in different places, possibly different colors.Dip the toothpick in the dishwashing liquid and then into the milk. You can dip it into the milk in several different places. What happens? Cutie Pie hypothesized the milk would ‘climb’ up the toothpick.
We also tried this with both food coloring and pepper at the same time! 
Of course, you can always just drop some food coloring in and mix it with your toothpick, but that isn’t nearly as exciting!So, what’s happening? The dishwashing liquid is reducing the surface tension in the bowl. It’s letting the water and milk spread out more, and when that happens the pepper and food coloring moves. When they move, they create patterns!
Like I said before, we are really enjoying the experiments in this book. They are simple, require mostly items that you already have in your pantry, and are fun!
(This book was given to us by a family member as a gift. We are not being compensated by Usborne Activities for this honest review and are only sharing out of our personal interest in science experiments. I am an affiliate with Amazon, which is the link I provided.)
That is sooo cool!!
Popping in from Pre-K Corner.
Very cool. We did this, but only with pepper. I’m going to check out that book.
Neat! Thanks for sharing! My kids all love Science experiments and I love simple ones like this that are easy to pull off. 🙂