Same S t u f f nt Diffe r rms Did you know that many of the things you may see or use e F o every day such as the water in a glass the air in a football and even the hard metal in a toy car are potential shape-shifters The substances that these things are made of can have the form of a solid a liquid or a gas The form they take depends mostly on their temperature When water gets cold enough it becomes a hard solid we call ice When it gets hot enough it becomes a wispy gas we call steam Many other substances behave the same way when they are heated or cooled enough A solid holds its own size and shape without needing a container If you pour water into an ice tray and freeze it the water will keep the shape of the cube-shaped molds in the tray You can think of the solid metal in a toy car as frozen too but its melting temperature is much higher than the temperatures we live in The person who made the car poured very hot liquid metal into a car-shaped mold and let it cool down and freeze A liquid does not hold its own shape If you pour a measuring cup of water into a tall glass or a shallow bowl it will take the shape of its container But that water does keep its own size It measures one cup Everyday liquids such as milk paint and gasoline act this same way Gases do not keep their own shape or their own size When air is pumped into a football it takes the shape and size of the ball As more air is pumped in the ball gets harder but not much bigger The air changes its size to fit the space inside the ball LEARN MORE READ THESE ARTICLES ENERGY TEMPERATURES VOLCANOES 8
LIQUIDS SOLIDS AND GASES S EA R C H LIG H T Mark whether each item below describes a solid S a liquid L or a gas G Some may match more than one form melts turns into a liquid has no shape or size is frozen keeps shape has no shape DID YOU KNOW If you’ve ever smelled gas coming from a stove you know it has an odd odor But cooking gas has no odor What you’re smelling is another gas with an odor that’s easy to notice It’s mixed with the cooking gas so that people know when there’s a leak is frozen S has no shape L G keeps shape S has no shape or size G Answer melts S turns into a liquid S G 9
S oundsThat Se e in theDark Hel-l-o-o-o-o-o A boy hears the echo coming from the hills Echo talk to me he calls to me repeats the echo to me to me to me What is an echo It’s a sound you make that bounces back to you from What if nothing stops the sound waves Then they just get smaller and smaller Or they are absorbed by soft things such as carpets draperies or large pieces of furniture That’s why we don’t usually hear echoes in the house hills or other surfaces But how can a sound bounce It’s not a ball Actually sound is a wave in the air If you could see air the way you see water you’d see the waves that sounds make Sound waves bounce only if they hit something big and solid like the side of a hill or the walls of a cave It is the D I D YO U K N O W i s s a i d t h a t a d u c k s q u a c k only sound that doesn’t echo If you long happen to have a duck and a l w a y y o u c o u l d t e s t t h i s t h e o r y hal yourself 10
ECHOES Did you know that echoes can help some animals see in the dark In pitch-dark caves bats fly easily never bumping into anything and even catching tiny insects in the air As they fly they make tiny whistlelike sounds These sounds bounce back to them The direction of the echo and the time it takes for it to return tell the bats exactly where things are as they fly Human beings have learned to harness the power of echoes for navigation too Submarines traveling underwater use sonar to bounce sounds off of solid objects so that they can tell where those objects are located sort of like undersea bats LEARN MORE READ THESE ARTICLES ENERGY RAINBOWS WAVES S EA R C H LIG H T What animal uses sound to see Dolphins do the same thing underwater Answer Bats use echoes to tell what is around them in the dark 11
