Light can travel through some materials, such as glass or water.

Light can also travel through empty space, like from the sun to Earth.

When light travels from one location to another, it goes in a straight line until it interacts with another object or material.

When light strikes objects through which it cannot pass, shadows are formed.

As light reaches a new material, it can be absorbed, refracted, reflected or can continue to travel through the new material; one of these interactions may occur or many may occur simultaneously, depending on the material.

Light can be absorbed by objects, causing them to warm.

How much an object’s temperature increases depends on the material of the object, the intensity of and the angle at which the light strikes its surface, how long the light shines on the object and how much light is absorbed.

Investigating and experimenting with temperature changes caused by light striking different surfaces can be virtual or in a lab setting.

When light passes from one material to another, it is often refracted at the boundary between the two materials and travels in a new direction through the new material (medium). For example, a magnifying lens bends light and focuses it toward a single point. A prism bends white light and separates the different colors of light.

Prisms and magnifying lenses can be used to observe the refraction of light. Visible light can be emitted from an object (like the sun) or reflected by an object (like a mirror or the moon).

The reflected colors are the only colors visible when looking at an object. For example, a red apple looks red because the red light that hits the apple is reflected while the other colors are absorbed.

Pitch can be altered by changing how fast an object vibrates.

Objects that vibrate slowly produce low pitches; objects that vibrate quickly produce high pitches.

Audible sound can only be detected within a certain range of pitches.

Sound must travel through a material (medium) to move from one place to another. This medium may be a solid, liquid or gas.

Sound travels at different speeds through different media.

Once sound is produced, it travels outward in all directions until it reaches a different medium. When it encounters this new medium, the sound can continue traveling through the new medium, become absorbed by the new medium, bounce back into the original medium (reflect) or engage in some combination of these possibilities.

Light travels faster than sound.

Some properties of objects may stay the same even when other properties change.

For example, water can change from a liquid to a solid, but the mass of the water remains the same.

Parts of an object or material may be assembled in different configurations but the mass remains the same.

The sum of the mass of all parts in an object equals the mass of the object.

When a solid is dissolved in a liquid, the mass of the mixture is equal to the sum of the masses of the liquid and solid.

Energy transfer (between objects or places) should not be confused with energy transformation from one form of energy to another (e.g., electrical energy to light energy).

The addition of heat may increase the temperature of an object.

The removal of heat may decrease the temperature of an object.

There are materials in which the entire object becomes hot when one part of the object is heated (e.g., in a metal pan heat flows through the pan on the stove transferring the heat from the burner outside the pan to the food in the pan).

There are other objects in which parts of the object remain cool even when another part of the object is heated (e.g., in a Styrofoam® cup, very little of the warmth from hot liquid inside the cup is transferred to the hand holding the cup).

The word “heat” is used loosely in everyday language, yet it has a very specific scientific meaning.

Usually what is called heat is actually thermal or radiant energy.

An object has thermal energy due to the random movement of the particles that make up the object.

Radiant energy is that which is given off by objects through space (e.g., warmth from a fire, solar energy from the sun).

“Heating” is used to describe the transfer of thermal or radiant energy to another object or place. Differentiating between heat, thermal energy and radiant energy is not appropriate at this grade.

Electrical conductors are materials through which electricity can flow easily.

Electricity introduced to one part of the object spreads to other parts of the object (e.g., copper wire is an electrical conductor because electricity flows through the wires in a lamp from the outlet to the light bulb and back to the outlet).

Electrical insulators are materials through which electricity cannot flow easily.

Electricity introduced to one part of the object does not spread to other parts of the object (e.g., rubber surrounding a copper wire is an electrical insulator because electricity does not flow through the rubber to the hand holding it).

Electrical conductivity is explored through testing common materials to determine their conductive properties.

In order for electricity to flow through a circuit, there must be a complete loop through which the electricity can pass.

When an electrical device (e.g., lamp, buzzer, motor) is not part of a complete loop, the device will not work.

Electric circuits are introduced in the laboratory by testing different combinations of electrical components.

When an electrical device is a part of a complete loop, the electrical energy can be transformed into light, sound, heat or magnetic energy.

Electrical devices in a working circuit often get warmer.

When a magnet moves in relation to a coil of wire, electricity can flow through the coil.

When a wire conducts electricity, the wire has magnetic properties and can push and/or pull magnets.

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