Look at this picture of Earth. You can see the continent of Africa. The rest of what you see is water in the form of oceans, clouds, and ice. The oceans are made of liquid water mixed with salt and other chemicals. The clouds you can see are tiny drops of liquid water floating in the air. There is ice around the poles because it is very cold there. Ice is solid water. It is the same materia…
Some of the water you drink comes from rivers. Some comes from rainwater that has soaked into the ground. All of this water originally came from the ocean. Eventually, it will go back to the ocean. This movement of water is called the water cycle. The water that you use every day has come from a river or from a well. It is brought to your home through many miles of pipes. Water from …
All the materials around you can be described as solids, liquids, or gases. Different materials melt at different temperatures. The chart shows the melting points of some materials you know. You might find some of these materials in your kitchen. Chocolate melts at about 97°F (36°C), which is just below body temperature. Chocolate feels good to eat because it melts in your…
Your clothes need to be washed when they get dirty. After they are washed, the water in them evaporates. When all the water has evaporated, the clothes are dry. You can help wet clothes dry quickly by spreading them out on a clothesline. Water evaporates faster when it is warmer. So the clothes will dry faster on a warm day than on a cold day. These aprons would dry even faster if there was a…
Metals such as iron and steel can be made into different shapes. Some iron shapes are made by melting the iron. The liquid iron is then poured into a mold. When it cools down, it becomes a solid again. The solid takes the shape of the mold. Molten iron being poured into a mold. Some objects get very hot when they are used, so they must be made of materials with high melting points. That wa…
The inside of Earth is very hot. In some places, it is hot enough to melt rock. Molten rock inside Earth is called magma. Lava is molten rock that comes out of volcanoes. When the lava cools down, it forms solid rock. The lava that flows from Hawaiian volcanoes is very runny. It flows a long way before it cools. Gradually the new rock builds up a cone. The lava from some volcanoes is more sticky.…
All materials are made of tiny particles. These are called atoms. Sometimes atoms join together to form molecules. Scientists talk about different materials by talking about these particles. They talk about how the atoms (or molecules) are arranged. This helps scientists explain solids, liquids, and gases. In solids, the particles are arranged in a regular pattern. They are held together by stron…
Most materials get smaller as they cool down. We say they contract. This means that a lump of solid iron will not float in liquid iron. Ice is different. Water contracts as you cool it down, but only until you get to 39°F (4°C). As it gets cooler than this, it starts to expand slightly. Ice forms at 32°F (0°C). Ice floats on water. This property of ice is very importan…
aerosol (AIR uh sol) — mixture of droplets of liquid in a gas atom (AT uhm) — tiny particles from which all materials are made basalt (ba SAWLT) — type of rock formed when lava cools quickly boiling (BOI ling) — when liquid is turning into a gas as fast as possible boiling point (BOI ling point) — the temperature at which a liquid starts to boil carbon dioxide (…
States of Matter. Carol Baldwin. Raintree, 2006. States of Matter. Robert Snedden. Heinemann, 2007. States of Matter: Gases, Liquids, and Solids. Krista West. Chelsea House, 2007. Volcanoes. Michael Woods. Lerner, 2007. http://ga.water.usgs.gov/edu/mearth.html USGS Water Science for schools. This site offers information on many aspects of water, along with pictures, data, maps, and interactive ac…