What is Diffusion?
Diffusion is the passive movement of molecules (solutes) so that they spread evenly into the available space. Solutes move from high concentration to low concentration (this is called moving down the concentration gradient).
Why is diffusion important?
This is how substances, like oxygen, cross cell membranes. Diffusion is awesome!
Try it! Place Skittles on a plate in a circle. Pour warm water over them. Wait.
Age Group: pre-k to 8th grade.
Transpiration! Root pressure pulls water up through the xylem (this type of movement in response to pressure is called a bulk flow. It is much faster than diffusion!) all the way to the leaves. Water is lost at the leaves and replaced by more water from the roots.
To see the process of transpiration in action you'll need:
1 celery stalk with leaves
Glass of water
Food coloring of your choice
Cut the end off the celery stalk so you can see the tiny holes (that's the xylem!). Mix the food coloring into the water, place the celery in, and wait about a day. The celery is still edible, so you get science and a snack!
Age Group: pre-k to 8th grade
Ariel Gilligan is a marine biologist and feminist (STEMinist hehe) mama trying to make science fun and relatable for her 4-year old. To see more of Ariel’s easy science fun, you can follow @home.science.fun.