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Key Concepts:

• Force
• Mass
• Newton's Laws of Motion
• Contact Force and Force at a Distance

Misconception Alert:

Speed, Velocity, and Acceleration: These three words can be very confusing to students because their scientific meanings are different from how we use them in everyday language.

• Speed is how fast something is moving. It is measured as a distance traveled in a period of time. This could be meters per second, miles per hour, inches per year, etc.)
• Velocity is the speed something is traveling in a specific direction. This could be meters per second upwards, miles per hour north, etc. An object can change its velocity without changing its speed. An example of this would be driving your car on a curve while keeping your speed constant. Your speed is not changing, but the direction you are traveling is, so your velocity is changing.
• Acceleration is a change in velocity. We tend to think of acceleration as increasing your speed, but you can also accelerate an object by slowing it down, or by changing its direction.

Covering the Basics:

To give your students a basic understanding of this topic, try the following.

1. An excellent way to introduce this topic is with The Old Table Cloth Trick. It exposes students to the concepts of inertia, friction, force, and mass, and it is dramatic, easy to master, and has many options for experimentation. I suggest you watch the video and master the skill, and start the unit with this dramatic demonstration, followed by having the students learn to do it themselves. You can easily adapt this to using books and paper instead of dishes and a tablecloth. Then have your students experiment to test the effect of different variables, such as the mass of the object, the texture of the cloth, the amount of force, etc. They should see that an object with less mass takes less force to move, which makes it very difficult to succeed with a plastic cup or bowl. The more mass you have, the more inertia you have to overcome, so the easier the demonstration becomes, up to the point that the weight creates too much friction to let you pull out the cloth.
2. Another excellent demonstration that incorporates all three of Newton's Laws of Motion requires only some weights and a bathroom scale. By using objects with different masses, and by altering the speed that you move them, you can see all three laws in action.
3. A fun way to test your students' understanding of Newton's Laws of Motion is to have them make predictions then test them with the Marbles, Inertia, and Paper Plates activity.
4. The High Bounce activity is a dramatic way to illustrate how the laws of motion affect collisions. It is easily adapted to experimentation by testing different balls (basketball, soccer ball, tennis ball, baseball, etc.) in each position (top or bottom).

   Ideas to explore:

   • What would happen if you stacked three balls instead of two?
   • Does the bottom ball bounce less than it would if dropped without the other ball? You may need to use the "frame by frame" video technique from Measuring Kinetic and Potential Energy to determine this.
   • What happens if the bottom object is something that does not have a lot of bounce, such as a book?

Quest: 6th Grade, Solar System

Some review questions about our Solar System. Quest: 6th Grade, Solar System

Nature of Science Potential

Most of these activities are excellent examples of the use of models in science.

Fun Facts

• The Earth rotates once every 24 hours. As it turns, if you are standing on the Earth, the moon seems to rise and set every day. Now, imagine you are standing on the Moon. How often would the Earth rise and set?
• If you stood on the Moon, holding a feather and a lead weight, and dropped them both at the same time, what would happen?
• Why can you sometimes see the moon during the day?
• Does the Moon rotate?
• Perihelion is the day each year when the Earth is at its closest distance to the Sun. You might expect that perihelion should happen in the summer, when it is warmest, and you would be right (but not in the way you think you are). Utah is cold at perihelion. How can that be?

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