STAAR Grade 5 Science

Matter is anything that has mass and takes up space. Everything around us is made of matter, including solids, liquids, and gases. Scientists identify and classify matter by observing its properties.

Physical properties are characteristics that can be observed or measured without changing the substance into something else. Mass is the amount of matter in an object, measured in grams (g) or kilograms (kg) using a balance. Volume is the amount of space an object takes up, measured in milliliters (mL) or liters (L). Density describes how much matter is packed into a certain amount of space.

Scientists often use water as a reference point to compare density. This is called relative density. An object that is less dense than water floats. An object that is more dense than water sinks. A wooden block floats because wood is less dense than water. A metal coin sinks because metal is denser than water.

Temperature measures how hot or cold matter is. Temperature is measured in degrees Celsius or Fahrenheit using a thermometer. When matter is heated, its particles move faster. When matter is cooled, its particles move slower.

Magnetism is the ability of a material to be attracted to a magnet. Iron, nickel, and cobalt are magnetic. Steel paper clips and nails stick to a magnet because steel contains iron. Plastic, wood, glass, and paper are not magnetic. Magnets have a north pole and a south pole; opposite poles attract and like poles repel.

An electrical conductor lets electricity flow through it easily. Copper, aluminum, and other metals are good electrical conductors. An electrical insulator does not let electricity flow easily. Rubber, plastic, glass, and wood are insulators. That is why wires are made of copper and covered with plastic.

A thermal conductor lets heat (thermal energy) move through it quickly. Metals are good thermal conductors, so a metal spoon in hot soup gets hot fast. A thermal insulator slows the movement of heat. Wood, plastic, foam, cloth, and air are good insulators, so pot handles and oven mitts are made of them.

Solubility is the ability of a substance to dissolve in another substance, such as water. Sugar and salt dissolve in water, so they are soluble in water. Sand, pebbles, and iron filings do not dissolve, so they are insoluble in water. Most solids dissolve faster in warm water than in cold water, and stirring also speeds up dissolving.

Physical state tells whether matter is a solid, liquid, or gas. A solid keeps its own shape and volume because its particles are packed tightly and only vibrate in place. A liquid has a set volume but takes the shape of its container because its particles are close together but can slide past each other. A gas has no set shape or volume; its particles spread out to fill any container.

Color, texture, shape, and size are additional physical properties that help identify matter. Luster describes how shiny or dull a surface appears. Hardness describes how easily a material can be scratched. Flexibility describes how easily a material can be bent without breaking.