SCIENCE STRAND II:
PHYSICAL SCIENCE
Commonly thought of as physics and chemistry, physical science for this level is limited to physical and chemical principles that can be observed and explored, and the inferences that can be made, based on concrete experiences that can be observed without complicated instrumentation or theories.
6. Recognize the advantages and/or disadvantages to the user in the operation of simple technological devices.
Advantages and/or disadvantages to the user refers broadly to a device’s mechanical advantage, or the ratio of the output force produced by a machine to the applied input force. The concept of mechanical advantage, rather than the term itself, is tested. For instance, an item might test students’ ability to recognize an advantage of using a ramp to slide a heavy box into a truck (less force is needed to move the object) in comparison with lifting the box straight up off the ground, as well as a disadvantage of using a ramp (the box must be moved through a greater distance). Simple technological devices are straightforward, mostly one-function devices that are real-life applications of the six basic simple machines (lever, wedge, pulley, wheel and axle, inclined plane, and screw): ramps, pliers, scissors, wheelbarrows, etc.
Students should understand that simple machines do not reduce work, but they commonly make an action less effort for people. Students should also know that the principle “you don’t get something for nothing” applies to simple machines: when a machine is used and the effort gets easier, something else (like speed, or the distance of the effort) is sacrificed. Students should be practiced at discussing the advantages and disadvantages of any simple technological device as they explore its functions and uses in a real-world context.
7. Predict the influence of the motion of some objects on other objects.
Students should have a practical understanding of Newton’s laws of motion: (1) an object will remain at rest or in uniform motion unless acted on by an outside force; (2) when a force acts on an object, it changes the momentum of that object, and this change is proportional to the applied force and to the time that it acts on the object; and (3) every action (force) is accompanied by an equal and opposite reaction (force). Students should be able to predict the motion of objects thrown or released by people who are in motion; identify or describe how the motion of one object can affect the motion of other objects; and identify or describe the apparent forces or impacts people can feel as a result of a change in an object’s motion. For instance, when an elevator begins descending rapidly, the people in it will have a slight “floating” sensation, and their feet will press more lightly against the elevator floor (since the people were at rest, their bodies tend to remain at rest even when the car moves downward). Another example would be when a rowboat is traveling from north directly south, a strong wind from the west would tend to change the boat’s direction to the southeast.
Among the fundamental concepts students should understand are that things move only when something moves them; they keep moving until something stops them; the harder something is pushed, the faster it goes; and the more massive something is, the harder it is to move. Students who can best apply those concepts are those who have observed many moving things and investigated why they moved and why they may have stopped.
8. Propose and/or evaluate an investigation of simple physical and/or chemical changes.
This outcome tests students’ abilities to distinguish between or identify changes that are physical changes only and changes that involve chemical changes; identify or describe procedures that would resolve investigations of physical and/or chemical changes; identify or describe the rate or nature of physical and/or chemical changes that are taking place; and evaluate how well a particular investigation or procedure measures physical and/or chemical changes. For test purposes, simple means observable, A physical change involves a change in the size, shape (configuration), or state of matter of a substance, without its producing or becoming a new substance, whereas a chemical change results in a permanent change in properties.
Simple chemical changes are very difficult to reverse, involve some kind of change in the properties of the material, and often give off heat on their own. Simple physical changes are more easily reversible and do not involve permanent changes in the properties of a material. Students should examine the characteristics of something before and after an event and use this type of analysis to decide whether a change is chemical or physical. Many common devices such as chemical “cold packs” or “heat packs” are in the range of student experience for this outcome, as are the effects of physical changes caused by water and chemical changes involving water and other common elements.
9. Provide examples of transformation and/or conservation of matter and energy in simple physical systems.
Students should be able to identify what type of energy transformation is occurring in a situation; identify or give an example (situation) of energy being transformed from one specific form to another; describe or identify something that performs a particular transformation of energy; and identify or describe how energy is conserved in a situation, or how matter can be converted into other matter plus energy (e.g., combustion), or how energy can be used in converting matter (e.g., photosynthesis). Students should have a basic understanding of potential and kinetic energy; the five main forms of energy (electrical, mechanical, chemical, thermal [heat], and nuclear); various types of energy conversions, one form to another; conversions of matter to energy, and energy to matter; and the laws of conservation of matter and energy.
In any system, energy must be accounted for, and students should be practiced in explaining how the energy in a given system has changed through an event. Because energy can be a difficult and abstract concept for students, students should be accustomed to discussing and describing familiar energy movements in their surroundings, such as those involved with a light bulb or a cup of hot tea. Specific names for the types of energy are learned as students use them in discussions and explanations.
10. Identify simple patterns in physical phenomena.
Simple patterns in physical phenomena includes such things as reflection and refraction of light and waves (e.g., in water); properties of waves (e.g., light and sound); production of highpitched and low-pitched sounds (vibrating columns of air); elasticity and/or compressibility of materials; seasonal patterns (e.g., light and shadows) due to orientation of sun and earth; daily or seasonal temperature patterns of land and/or water; and movement of heat in a system and/or factors affecting heat movement (e.g., surface area). Students should be able to identify, deduce, and/or explain simple patterns and relationships from text, graphs, charts, drawings, or prior knowledge.
Patterns can also be the generalities that students infer from a broad range of observations; students should understand that while there may be some irregularities in events or phenomena they experience, an underlying pattern can often be found.
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