School Improvement in Maryland

Using the State Curriculum: Science, Grade 5

Skills and Processes | Earth/Space | Life | Chemistry | Physics | Environmental

Lesson Seeds: The lesson seeds are ideas for the indicator/objective that can be used to build a lesson. Lesson seeds are not meant to be all-inclusive, nor are they substitutes for instruction.

Standard 5.0 Physics

Topic D. Wave Interactions

Indicator 3. Provide evidence to show that light travels in a straight line until it is reflected or refracted.

Objective c. Observe and describe that a ray of light changes direction when it crosses the boundary between two materials such as air and water or air to glass.

Lesson Name

Change in direction of light at a boundary

Activity

Refraction of light in an aquarium

  • Fill a clear glass 5 gallon aquarium with tap water and add one-half teaspoon of powdered milk (coffee creamer).
  • Stir to mix.
  • Hold a laser pointer above the surface of the water and ask students to predict the pathway of the laser beam after it enters the water.
  • Shine the laser pointer into the water and compare the angles.
  • Did the beam bend toward the surface or away from the surface of the water? If students are uncertain, add chalk dust or talcum powder to the air above the aquarium and repeat the demonstration.

The angle of reflection can also be demonstrated using the same aquarium.

  • Shine the laser pointer at an angle from the side of the aquarium toward the surface of the water. The beam will reflect from the surface, downward toward the opposite side of the aquarium.

A Light Maze

  • Stand a thick textbook up on the desk like a tent.
  • Shine a flashlight or laser pointer on one side of the book.
  • Use three plane mirrors to make the light shine on the other side of the textbook without moving the flashlight or the book. Draw a diagram of each plan and explain why it worked or did not work.

Safety issue: Caution students to avoid looking directly into the beam of the laser.

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