You can huff and puff, but no matter how many times you blow a bubble, it always ends up round. This is because the molecules in the bubble mixture pull on each other, like a group of friends holding hands in a circle. The pulling means that you end up with a shape that has the smallest amount of surface area—a sphere.
Is there a way you can trick the natural forces that make bubbles round into making a bubble that's square? Let's find out!
Is it possible to blow a square bubble?
- 1/4 cup liquid dish soap
- 2 tablespoons glycerin
- 4 cups water
- 6 drinking straws
- Plastic pipette
- Before you start, think about the liquid bubbles you always blow: What shapes are they? Think about the stick you dip into bubble solution to blow the bubbles. What shape is it? Write down any notes in your notebook.
- Using your notes, guess if your attempts to blow a square-shaped bubble will work. Write this guess—called a hypothesis—in your notebook.
- Fill the bucket with the liquid dish soap, glycerin and water, mixing the solution around gently with your hand.
- Cut all of your straws in half. You should now have 12 mini-straws.
- Assemble 4 pieces of straw into a square shape. Use a pinch of clay to keep the straws in place.
- Repeat this with 4 additional pieces of straw so that you have two squares.
- Use the 4 remaining pieces of straw and clay to join the two squares together; now you have a cube!
- Cut the bulb end off the plastic pipette; this will be your bubble blower. If you don't have a pipette, use another plastic straw instead.
- Head outside to start your bubble testing!
- Carefully dip the straw cube into the container of bubble solution. Be sure the straw cube is completely covered with the bubble solution.
- Gently lift the straw cube out of the bubble solution. Each part of the cube should now have a film of bubble solution inside of it.
- Dip the pipette into the bubble solution.
- Blow into the small end of the pipette to make a bubble come out of the larger end.
- Gently place the bubble into the middle of your cube. This bubble will end up in the center of the cube.
- Write or draw your observations (the things you see) in your notebook.
The bubble you blew and placed into the cube should have centered itself. The "side" bubbles in the straw cube should push against this "center" bubble, forcing it into a square shape. If you pop the side bubbles, the bubble in the middle will become round again.
Bubbles are round because a sphere is the shape that is the most stable for them—a sphere is more stable than a square or a triangle or any other shape. But when a bubble is surrounded by other bubbles, these "side" bubbles push against the "center" bubble, squishing and squashing until it has corners and sides—like a cube! That's what happened to your bubble.
Now that you've made a cube-shaped bubble, keep the science going by trying your hand at different shapes. If you make a pyramid out of straws, can you end up with a triangular bubble in the middle? Can you make two or more bubble shapes by connecting straw cubes? How about if you don't cut the straws in half, and use whole straws to make a really huge straw cube? Do you end up with a really huge square bubble, or just a big mess? Guessing and testing is a big part of the scientific method, so write down what you think will happen and head back outside for more experiments.