Science Assessment

Students should know that:

1. Two objects (or quantities of a solid, liquid or gas) must be in contact with each other for energy to be transferred by conduction. Energy can also be transferred from one part of an object to another by conduction.
2. There must be a temperature difference between the objects or samples of matter in contact or there must be a temperature difference within a single object for energy to be transferred by conduction.  The greater the temperature difference the greater the amount of energy that can be transferred by conduction and the faster the transfer occurs (assuming the material making up the objects and their masses are held constant).  As the temperatures of the two objects get closer together, the rate of energy transfer slows down.
3. The energy transferred by conduction goes from the warmer matter to the cooler matter not from the cooler matter to the warmer matter.
4. As energy is transferred from the warmer to the cooler matter by conduction, the thermal energy (and temperature) of the warmer matter will decrease and the thermal energy (and temperature) of the cooler matter will increase until the objects or samples are at the same temperature.  [This sub-idea assumes that neither object or sample of matter changes state, in which case the temperature would not increase or decrease while the change of state was occurring.]
5. During conduction, energy is transferred without the transfer of matter. This is unlike convection, where matter and its energy move from one location to another together.

Boundaries:

1. Assessment items do not assess the idea that conduction occurs through collisions of atoms.  This idea is covered under the advanced conduction idea.
2. Items do not ask students to make calculations about how much energy is transferred by conduction (e.g. they will not be asked to make calculations given mass, heat capacity, and temperature).
3. Assessment items assume a net transfer of energy from the warmer object to the colder object without referring to it as a net transfer.
4. Contexts of assessment items will be limited to those that do not involve changes of state.

Students should know that:

1. Energy can be transferred by light when light from the light source shines on another object (receiver). For example, when a light bulb (or the sun) shines light on an object, energy is transferred from the light bulb (or the sun) to the object.
2. Light transfers energy through space; it does not need a medium such as air or another object in order to transfer energy from one object to another.
3. Light is given off by objects in all directions [except for lasers and other specially designed light sources or when the light is reflected or blocked] and travels in straight lines; therefore energy can be transferred from an object by light in all directions to any object in the path of the light.
4. Because light is transferred in all directions, the amount of energy transferred by light from a light source to an object decreases as the distance between the source and object increases.
5. The amount of energy transferred by light depends on the color of the light source. Light sources can give off light of different colors, ranging from red [through orange, yellow, green, blue] to violet.  For a given period of time and equal brightness, violet light can transfer the highest amount of energy and red can transfer the lowest amount of energy.
6. The amount of energy transferred by light depends on the brightness of the light source.  The brighter the light, the more energy can be transferred.  The dimmer the light, the less energy can be transferred.
7. The longer a light source shines on another object, the more energy is transferred from the source to the object.
8. When an object absorbs light, the object gets warmer, (unless energy is transferred away from the object), which means the thermal energy of the object typically increases.  For example, when the sun shines on a person, the person’s body becomes warmer.  When an object gives off light, the object gets cooler, which means the thermal energy of the object typically decreases (unless additional energy is supplied to the light source (e.g. a lamp plugged into an electrical outlet)). For example, as a glowing hot piece of metal cools, some of the temperature decrease is due to the fact that light is being given off. [This sub-idea assumes that neither object changes state, in which case the temperature of the object would not increase or decrease.]

Boundaries:

1. Students are not expected to know that all objects give off “electromagnetic radiation.”  This idea is limited to visible light.
2. Students are also not expected to know that the temperature of the object the light shines on increases asymptotically.  Items use time periods during which the temperature of the object noticeably increases the longer the light shines on the object.
3. Contexts of assessment items are limited to those that do not involve changes of state.