In this Rosie Labs guide you will find:
- Productive struggle opportunities for students during their project build,
- Lesson objectives and concept overview,
- Optional STEM topic video to share with participants,
- Step-by-step instructions and video of the Rosie Riveters’ Milk Painting Project,
- Optional STEM activities to further explore the objectives and concepts used in the project build.
Objective
Students will learn about the properties of and changes in matter while making their own Milk Paintings!
Concept Overview and Experiment Inspiration
Everything on earth that takes up space is called matter. Even you! Matter is made up of tiny particles called molecules. Molecules are super small, and we can’t see them, but trillions and trillions of them make up you, me and everything around us! And depending on how these teeny, tiny molecules are arranged (put together) in a given space, they form different types of matter.
Each arrangement, or state of matter, has properties. Properties describe how something looks, feels, or acts. In this project you’ll spend some time exploring some of the properties of a liquid, or more specifically, milk!
One property of liquids is that they take the shape of their container. If you were to pour your milk into a glass, it would take the shape of the glass. If you pour milk into a bowl, it takes the shape of the bowl. Liquids move around. The molecules in liquids are farther apart than those of solids, so they can move around more and even roll around each other. This movement of molecules is why liquids take the shape of their container.
Even though liquid molecules are farther apart and like to move, the ones resting at the top of a container like to hold hands, creating almost like a skin at the top of the liquid that has some strength. If you were to pour your milk into a glass and gave the glass a little jiggle you would see that the milk at the top of the glass doesn’t seem as loose as the rest of the milk, and when it moves, it looks like it moves as one piece. This tendency in liquids at rest is called surface tension.
Surface tension can be changed by adding certain types of matter to the liquid. For this experiment, students will change the surface tension of milk to make a painting. First, it’s important to note that milk consists of a lot of different types of molecules, including fat, water, sugars, vitamins, and minerals. Soap is attracted to both water molecules and fat molecules. When we add a bit of soap to our milk, we move the molecules around and alter the surface tension. Some of the fat molecules move toward one part of the soap and the water molecules move toward the other part of the soap, making space between the molecules!
In this project you’ll experiment with milk, soap and food coloring to see what happens when soap gives food coloring the space it needs to burst through your milk!
Science Goals
- Matter is everything around us; it has mass and is made up of molecules
- Liquids take the shape of their containers. Liquids at rest form surface tension.
- Surface tension is the cohesion, or attraction, of liquid molecules at rest. These connected molecules can hold up objects that are lighter or less dense than the water.
Vocabulary
Molecules-two or more atoms joined tightly together. The number and kinds of atoms in a molecule and the way they are arranged will determine the matter (or substance) the molecules create.
Matter– anything that has mass (or weight) and takes up space. Matter is made up of molecules
Property– a trait or description of how matter looks, feels or acts
Surface Tension– the cohesion, or attraction, of liquid molecules at rest. These connected molecules can hold up objects that are lighter or less dense than the water.