Changing the forces: how living things fly

This lesson asks you to describe ways in which the four forces of flight can be altered, and to describe the characteristics and adaptations that enable organisms to fly. The museum offers NASA Glenn's explanation of how the ratio of lift to drag sets a glider's descent angle, and what al-Jahiz says of creatures that fly on two wings; ways of altering the forces, such as wing size and angle, and the body features of birds and insects, have to come from another source in your class. ¹

Make two identical paper gliders and change just one thing on one of them, such as folding its nose. Release each gently from a low place and compare how far they glide. Which force do you think you changed, and what is your evidence?

Compare a bird's wing and an insect's wing from pictures. Write what they share and how they differ, and what that says about what a living thing needs in order to fly.

In the editor's list, the third part of Kitab al-Hayawan opens with the chapter on pigeons "and the kinds of knowledge God placed in them", then takes up, among others, the kinds of flies, crows, dung beetles, the hoopoe, the Egyptian vulture and the bat ^{2 3}. Elsewhere al-Jahiz says that wisdom may show more plainly in the fly, small as it is, than in the splendid horse, and that he does not dwell on the great-bodied for their size ^{4 5}.

Al-Jahiz notes that not everything that flies on two wings is a bird, and that locusts, bees and flies are not called birds ⁶. Choose two flying creatures you know and list what their wings share and how they differ. Does your list help you decide what the word "bird" should mean, and why?

• Kitab al-Hayawan: the seven parts chapter by chapter, and how the editor describes the book.
• al-Jahiz: what the Encyclopaedia of Islam says of his life, and where the sources differ on the year of his birth.
• Ibn Firnas's reported winged flight: NASA Glenn's glide angle, and its modern paper example.

In the record of Ibn Firnas's attempt you will find NASA's paper example of one unit of height lost across ten horizontal units. Draw it on squared paper, then draw the case where the same height is lost across only five units, and compare the two slopes.