Archive for the ‘physics’ Category

Sink or float?

Walking back from lunch, my 5 year old son, J, said that he had an idea for a science experiment. He wanted to see if his coin sinks or floats in his empty chocolate milk container. When we got home, we conducted the experiment and quickly realized that the plastic coin that he wanted to use for the experiment wouldn’t fit in his milk container, so we pulled out a small plastic container for the experiment and found some more items to test.

We’ve done sink/float so many times since J was able to throw things into the water. My favorite was an impromptu sink/float lesson at a wedding reception. I didn’t want to crush J’s enthusiasm for science, so I let him lead. I also encouraged him to fill out his science notebook which he loves, especially now that he’s learning how to write. He wrote down what items he wanted to test and hypothesized with an “S” or an “F” if he thought they would sink or float, respectively.

He thought the plastic coin would sink, the penny would sink, and the Duplo block would float.

Here’s what he learned: His special coin floated. The penny sank. The Duplo floated, but then he flipped it upside down and it sank! 

He loved when he was right, but he also loved finding that the Duplo both floats and sinks!

It turns out that the Duplo is made with a lot of empty space underneath. When that space is filled with air, the block floats. When the space is filled with water, the block sinks. We love science!



My son (Z, who is 3 years old), got a little flashlight as a birthday party favor. “Look, Mama! Little!”

“Cool! Can you make the light big?”

“Neat! Can you make it little again?” Z repeated this a few times before getting bored. The next day, he asked for the flashlight again. I suggested something new. “Can you make a small light on the wall?”

“Yup, that works. Can you make a big light on the ceiling?” He was pretty good about appeasing me. I tried to get him to say what exactly he was doing along with his actions, but wasn’t successful. Producing a small light on the ceiling just made him giggle.

Doing science doesn’t have to be complicated, with the whole scientific method and so on. Try something, and try something else. And then try a variation or two. Adam Savage says:

Guess I’ll do the writing for Z for a little while.