Lesson Title: SOH-CAH- TOA- What?
Curriculum Area: Math
Technology Strand: Societal Issues
Grade Level: 8
Essential Question: How can trigonometric ratios help find missing angles or sides of right triangles?
A Activity Summary This activity is designed for 8th graders in Geometry or Algebra I who are using trigonometric ratios for the first time. In this lesson, students will learn how to find a missing angle or side of a right triangle, using the TI-83 Plus calculator.
C Curriculum Math
1.01 Use the trigonometric ratios to model and solve problems involving right triangles. The learner will identify and use the trigonometric ratios to solve problems with right triangles.
T Technology Societal Issues
3.01 Select and use a variety of technology tools to collect, analyze, and present information.  
Activating Strategies
Hot Seats
1. Prior to the beginning of class, the teacher will prepare questions related to the topic of study and write them on sticky notes.
2. Place the sticky notes underneath student desks/chairs so that they are hidden from view.
3. At the start of the class, inform students that several of them are sitting on "Hot Seats" and will be asked to answer questions related to the topic of study for the day.
4. Have students check their desks/chairs for the strategically placed sticky notes.
5. Students who have questions on sticky notes will then take turns reading the question and attempting to provide an answer. Due to the nature of this motivational activity, these should be questions that students are able to answer.

Hot Seat Questions and Answers
1. When given 2 angles of a triangle, what theorem helps you find the third angle? (Angle Sum Theorem)
2. In a right triangle, if you know the length of 2 of the sides, what theroem do you use the find the length of the third side? (Pythagorean Theorem)
3. What is the sum of all the angles in a triangle? (180 degrees)
4. What is the Triangle Inequality Theorem? (The third side of a triangle is between the sum and difference of the first two sides.)
Technology Vocabulary:
Detailed Technology Instructions:
Cognitive Teaching Strategies
1. Prior to class, download and print a class set of the KWRT.doc. Distribute to the students. Go over the key vocabulary words and the parts of a right triangle.
2. Write the phrase “SOH-CAH-TOA” (It is pronounced "so - ka - TOE - ah") on the overhead or dry-erase board. Explain that this phrase is used as a mnemonic device for learning the ratios for sine, cosine, and tangent. The first letter of each word gives the ratios.

SOH: Sin A = Opposite leg / Hypotenuse
CAH: Cos A = Adjacent leg / Hypotenuse
TOA: Tan A = Opposite leg / Adjacent leg

3. Prior to class, download and print CLVG.doc. Make one copy per student. While in the computer lab, go to http://www.mathtv.com/Trig/pages/ch02/ch02_s3.htm to play a video of the trigonometry lesson. Play the footage of the first problem. Instruct the class to write down significant ideas, concepts, phrases, steps, etc. on the left-hand side of their paper from the video. Students should be instructed to be brief and use abbreviations as needed. Notes should be recorded in sequential order.

a. First, press PLAY, which is the arrow.
b. If you want to FAST FORWARD hold down the left clicker and drag the sliding knob to the position where you want the clip to play. Same procedure for REWIND.
c. When you want to stop the clip, press the STOP button.

4. You can play the video as a class or you can have each student play the video and listen through the head phones. Using the headphones will allow the students to replay the video if they miss something they felt was important.
5. Stop the video after the first problem and have students share notes. Have students write down any information that their partners had considered important but they did not list on the right side of their paper.
6. Go over the video as a group discussing the important concepts and ideas in the video. Give students a chance to use the TI-83 to find the answer to problem #1.

a. Press MODE and highlight DEGREE then press ENTER.
b. Press 2nd Key and press the MODE key to quit.
c. Key in the expression in the exact way it looks on paper after performing the Algebra and press ENTER. Be sure to point out the SIN, COS, TAN, SIN-1, COS-1, and TAN-1 keys.
d. Make sure students understand they will need to press the 2nd key before pressing the inverse trigonometric function keys(any key that has -1))

7. Have students play the rest of the video writing down important information. Advise student to practice keystrokes along with the video and summarize the lesson at the bottom of the CLVG paper when finish reviewing all of the problems from the clip.

Question and Answer Session
a. What information has to be given in order to find the measure of an angle using a trigonometric ratio? (You must have at least 2 sides)
b. What information has to be given in order to find the measure of a side using a trigonometric ratio? (You must have at least one angle and a side)
c. Does it matter what mode the calculator is in? (Yes, because the calculator must be in DEGREE mode)
d. Do you use the inverse function key when finding a side or angle? (When you are finding an angle)

8. Prior to class, download and print TRIGWS.doc. Make one copy per student. Put students in pairs to complete the worksheet.
9. Review answers and calculators strokes.
Summary Strategies
To engage students in synthesizing major concepts in this summary strategy
Using the "Shaping Up" Review, students will synthesize major concepts from the lesson using four different shapes. By varying the manner in which students visually summarize their learning, retention of the information learned is increased.

1. Download and print review.doc Make enough copies for each student.
2. In "The Heart," have students write one thing that they loved learning about in the lesson being reviewed.
3. In "The Square," have students write four things that they feel are important concepts from the lesson being reviewed. One concept should be placed in each corner.
4. In "The Triangle," have students write the three most important facts they learned from lesson being reviewed. One fact should go in each corner.
5. In "The Circle," have students write one, all-encompassing (global- like the circle) statement that summarizes all of the important concepts and facts learned in the lesson being reviewed.
6. Collect the review sheet and assess student learning.
Click for directions on how to download files on a Windows computer. 
TI-83 Graphing Calculator
Laptops or computers with Internet access for each student
headphones (optional)

Microsoft Word Files

Internet Website
Re-teaching and Enrichment Activities

The concept for this lesson plan was submitted by 
Nicia  George
Allen Middle, Data last modified: 3/21/2006