Introduction
Begin a class discussion and ask the students if they have ever seen a sailboat. Assuming there are some “yes” responses in the group, ask the students what they noticed about the design of the sailboat. Hopefully, someone will say their sails are triangular. Ask students why they think the sails have this shape. Explain that the sails are designed in a way that allows the boat to take advantage of winds at 90 degree angles by way of “tacking.” The sail design enables the boat to move in previously inconceivable ways. Pass out a copy of “How does a Sailboat move upwind?” https://www.physlink.com/Education/AskExperts/ae438.cfm to each student and hold a class discussion about how the sail design works. Write key points on the board.
Day 1
• Define a right triangle and identify the legs and the hypotenuse of the triangle.
• Provide the formula for the Pythagorean Theorem, a2 + b2 = c2, and identify a and b as the legs and c as the hypotenuse.
• Distribute the Pythagorean Theorem Handout and walk the students through each of the four examples.
• Give the students about ten-fifteen minutes to work on the Student Practice problems.
• Invite a few students to put their answers to the problems on the board and explain their work to the class.
• Ask the class if they agree with the work on the board and if they solved the problems in a similar fashion
• Answer any remaining questions about the problems.
• Tell the students that they will be using the information they learned today to design sailboat sails in the next lesson.
Day 2
Introduce the lesson as a follow-up to yesterday.
"Today we will do an 'experiment' to see if the Pythagorean Theorem really works. We have learned about sailboat design and learned how to calculate the missing side of a right triangle, but how can we be sure this is true?"
• Distribute Sailboat Handout, rulers, and two post-its to each student.
• Instruct each student to measure 2 sides of each of the triangular sails on the handout and record their answers on their post-its.
• Students calculate the measure of the third side of the triangle using the Pythagorean Theorem.
• Students then measure the third side of the triangle and compare their answer to the one they got in the previous step.
• Students record and summarize what they notice.
• Students decorate their sailboats as they choose and write a brief summary on why their sailboat sail design works.
Wrap-up
Depending on your classroom, allow students to display their work for a “gallery walk” where they are able to see what other students created.