When you inflate a soccer ball, it gets harder because of particles. Air particles are being compressed into the container and pushing on the inner walls of the ball. If the ball is placed in the freezer, the ball will deflate a little bit because the particles get closer together in the cooler temperatures.
All matter is made of particles that are too small to be seen.
Everything you can see and touch is made of matter. It is all the “stuff” in the universe.
Things that are not made of matter include energy, and ideas like peace and love.
Matter is made up of small particles that are too small to be seen, even with a powerful microscope. They are so small that you would have to put about 100,000 particles in a line to equal the width of a human hair!