Draft: this lesson was written with AI help and has not yet been read by a human editor.
1 What your class asks
This lesson asks you to name natural and artificial sources of light, and to describe properties of light: that it travels in a straight path and that it can be absorbed, reflected and refracted. The museum offers one scholar's experiments on how light travels and his naming of reflection and refraction among the states of light; the light sources in those experiments include the sun, the moon, a star and a candle. Absorption and sources of your own are for your class to investigate. 1
Curriculum expectations, with their official codes
- C2.1 identify a variety of natural and artificial light sources
- C2.3 describe properties of light, including that light travels in a straight path and that light can be absorbed, reflected, and refracted
2 Before you start
A thought to carry into the lesson.
3 The lesson
How could you test that light travels in a straight path?
The expectations ask for a property of light and for the sources that give it. Think of a test with a source, a small opening and a screen, and of what you would block or measure to check the path.
Go deeper
In Ibn al-Haytham's dark room, sunlight enters through a small hole. In dusty air the light can be seen stretching straight from the hole to where it falls 2. Set an opaque body on that line and the light vanishes from the spot beyond; take the body away and the spot returns. Lay a ruler along the line and the light keeps to its edge 3. He says the same holds for the light of the moon 3, and for a bright star on a night without a moon 4.
Think about it
Ibn al-Haytham tried the sun, the moon, a star and candles, and the light kept to a straight line each time. Why is a claim about light more convincing when it is tested with several sources than with only one?
Into the museum
- Ibn al-Haytham's dark room: the sunlight, starlight and candle tests, step by step.
- Optics: the three conditions of light he studied, travelling straight, reflected and bent.
- Ibn al-Haytham: who he was and what else he wrote.
Try this
Read about Ibn al-Haytham's dark room. List the sources of light it names, then sort them into natural and artificial.
4 Check yourself
Nothing here is marked or sent anywhere. It is for you.
In your own words: what does Optics have to do with this lesson?
Compare with the card
Three states of light. Optics is the study of light and vision. The editor of the Kitab al-Manazir notes that the Greeks treated optics as a branch of mathematics, while Ibn al-Haytham made it a mixed science of natural and mathematical kinds and studied light in three states: travelling in straight lines, reflection and refraction. Which of these three have you already seen in everyday life?
In your own words: what does Ibn al-Haytham's dark room (the camera obscura experiments) have to do with this lesson?
Compare with the card
A dark room and a hole. Ibn al-Haytham let the light of the sun, the moon, the stars and a fire into a dark room through a small hole and studied it on the opposite wall. He cut its path with an opaque body and laid a ruler along it, and found it perfectly straight. With several candles before one hole, a spot of light appeared opposite each candle along a straight line through the hole. What does this show about how light travels?
I can now
Notes
- 1. Ontario Ministry of Education, The Ontario Curriculum: Science and Technology, Grades 1–8 (2022)
- 2. Kitab al-Manazir, Books 1-3, ed. Abd al-Hamid Sabra (Kuwait 1983), p. 73
- 3. Kitab al-Manazir, Books 1-3, ed. Abd al-Hamid Sabra (Kuwait 1983), p. 74
- 4. Kitab al-Manazir, Books 1-3, ed. Abd al-Hamid Sabra (Kuwait 1983), p. 75