# BROKEN SPEAR

(c) 2022 George Gadanidis & Janette M. Hughes

Topics: refraction; properties of light; scientific discovery

The Broken Spear activity is designed to have a low floor and a high ceiling and may be used across a number grades. It introduces students to light and its properties, which are addressed in increasing levels of complexity in the elementary science curriculum.  For example, in Ontario, Grade 4 students:

• “investigate the characteristics and properties of light”
• “conduct experiments to show that light travels in a straight path, that light reflects off of shiny surfaces, that light refracts [bends] when passing from one medium to another”
• “describe how different objects and materials interact with light (e.g., prisms separate light into colours)”.

1. IN A STORY

• PAUSE ON PAGE 7
• How could you slow down when sledding down a hill?
• How could you turn left? Why would this work?
• How could you turn right? Why would this work?
• PAUSE ON PAGE 11
• Why do you think Arda and Orta keep missing the fish in the water with their spears?
• PAUSE ON PAGE 18
• Why do you think the spears look bent or broken in the water?
• What may be the connection between how a sled changes direction in snow and how a spear looks broken in the water?
• PAUSE ON PAGE 20
• How is Arda’s life different from yours?
• What might you learn if you lived in Arda’s time that you don’t know today?
2. SCIENCE EXTENSIONS

#### 2.A. Broken pencil experiment

• Fill a see-through container with water.
• Insert a pencil in the water at an angle, so part of the pencil is in the water and part out of the water.
• Observe it from different angles.
• Record your observations using diagrams and words.
• Add possible explanations for what you observe.
• Connect with Arda’s experience sledding down a hill: How may the pencil appearing to be bent or broken be similar to turning left or right when sledding?

#### 2.B. Turning car experiment

• Use a book or other flat surface to create a ramp.
• Let a toy car roll down the ramp and notice that it rolls in a straight line.
• Use layers of masking tape to create a bump on one side of the ramp.
• Let the toy car roll down the ramp again, so that one of its front wheels rolls over the bump.
• Notice how the car’s motion changes.
• Record your observations using diagrams and words.
• Connect with a thought experiment:
• Imagine a rectangular prism travels through the air and hits the surface of a still lake at an angle.
• Will the object continue in its path as it hits the water?
• Will it turn? If yes, in which direction? Why?
• How may this be similar to what you noticed about the car’s motion?

#### 2.C. Rainbow experiment

• Use a light box to shine a white light through a prism and notice that the light separates into the colour spectrum. Or, search the Internet for a video demonstration of this phenomenon.
• Record your observations using diagrams and words.
• Add possible explanations for what you observe.

#### 2.D. REFLECT

• How are the above experiments similar and different?

#### 2.E. AN INTERNET SEARCH

• Conduct an Internet search on the word REFRACTION.
• List and describe 2 science ideas that you have learned or understood better.

#### 2.F. What did you DO in science today?

Imagine someone in your family asks you: What did you do in science today?

Script a dialogue that would share what you learned in a way that would offer a science surprise.