Teaching Framework:
Instructional Translation of Indicator:
(Indicator) The student recognizes and describes examples of Newton’s Laws of Motion.
Teaching Concepts:
(A) (Prior Knowledge) Prior to addressing indicator concept, students must understand acceleration, force, and mass.
(B) (Misconceptions) Many students think of mass and weight as the same. mass is how much matter (stuff) is in an object. weight is the effect of gravity pulling down on that mass. If they do not understand the differences yet, remind them of the difference and use correct terminology when discussing the concept. If the students use the term weight instead of mass, correct them and move on. Do not try to teach both concepts at the same time.
(C) (Indicator Concept) During this lesson, students will learn descriptions and examples of Newton’s Three Laws of Motion.
(D) (Misconceptions) Students often do not understand what forces are involved in the motion of objects and why objects curve or move straight. Don’t let this material intimidate you. Children ask questions about this stuff all the time, and even the smallest exposure to this topic can provide a good base!
Students often interpret Newton’s 1st law with a lack of complete understanding. An object in motion should stay in motion unless acted on by another force. If you take a book and slide it across the table, it quickly comes to a rest, yet no one touched the book and caused it to stop. friction is a force and acts in an opposite direction from motion. friction acts to slow objects down.
Students believe that an object sitting on a table, not moving, has no forces acting on it. As stated in the Item Specification section, gravity is acceleration. Therefore if the object has mass, there has to be a force acting on it. The table is simply providing the equal and opposite reaction in the direction the object is trying to move, which is down. This is the same reason we don’t fall through to the center of the earth. The earth (or whatever we’re standing on) stops us!
Students believe that an unmoving object does not have a force acting on it until it moves and that a force causes it to move. However, if there is gravity, there is already a force acting on the object, hence there is already movement. An additional force acting on the object does not cause movement (the object is already being pulled by gravity) then, it causes acceleration. If the object is already moving, it doesn’t need a force to keep moving. It would, however, need a force to speed up, slow down, or change directions.
Students will confuse the effects of forces with the actual forces. Be sure to clarify this. In everyday language, forces push or pull on an object.
Essential Vocabulary Terms and Definitions:
force – Any push or pull on an object.
mass – The amount of matter in an object.
acceleration – The rate at which velocity changes (how quickly an object speeds up or slows down).
velocity – The speed and direction an object is moving.
inertia – The tendency of an object to resist motion. More mass equals more inertia.
gravity – The attraction between two objects because of their masses.
weight – The force of gravity acting on an object.
newton – Unit of force (N), 1N = 1 kg * m/s2
friction – A force that opposes motion of objects that touch as they move past each other.
free fall – The movement of an object toward earth because of gravity.
equilibrium – An object under equal but opposite forces.