Table of Contents Module 3 PROCEDURE
Part I: Features of Sails Classroom - 20 minutes
1. Place the word “sail” on the board. Access Prior Knowledge: Ask students, “Have you ever seen a sail before, what are they used for?” and have a student draw one on the board. Ask students, “What are some of the features of sails? When do you see sails?” Originally, sails were rectangular in shape in order to use the wind to “push” boats forward. Sailors used the trade winds to leave from port and to eventually sail home again. Show students an image of an early sailing vessel with rectangular sails.
2. Ask students, “What are some limitations of only using the wind to push your boat, downwind sailing?”
3. Ask students, “What shape are most of the sails we use at the Sailing Center? (triangular) Today we are going to calculate the area and perimeter of a few of our sails? What are some of the reasons we may want to calculate area of our sails? Generate student response: order new sails, to calculate the area of our sails to compare sail area to boat speed, or to identify situations in which sailors would benefit from reducing sail area. Why do certain sized sails go on certain boats?”
Part II: Measuring Surface Area of Sails Outdoor Classroom - 40 minutes
Note: The main sails are not perfect right triangles, and kids may notice this. If they do, explain that you can still use right triangles to measure the existing sail area on the leech.
1. Tell students, “Today we are going to learn more about our sails. We will calculate the area of the main sail and jib sail and the main sail of a laser or other sails.” (Use sails that are easy to move and measure.) This is one way that we can use math in other parts of our life.
2. Roll out a sail and review the parts of a sail with the class. Relate the parts of a sail to your body, head at the top, foot at the bottom, then luff, leech, tack, and clew.
3. Ask students, “How do we measure the perimeter and area of a sail?” After students respond, put the formula for Sail area on the board. Area of a triangle = ½ Base (foot) * Height (luff.) Show students a rectangle is made of 2 triangles.
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