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Lesson Plan

Below is my lesson plan on Equilateral Triangles. I tried to upload it through google docs but the format was off and all of my boxes came up blank ūüė¶



UNIT NAME: Triangles DATE: March 5, 2011




  • What is an equilateral triangle?
  • What are some properties of equilateral triangles?
  • What relationship do the angles and sides of equilateral triangles have?
  • How can we construct an equilateral triangle?



  • How can you draw and prove an equilateral triangle using Geometer‚Äôs Sketchpad?

USA- ISTE: National Educational Technology Standards for Students: The Next Generation

‚ÄĘ Standard:¬†1. Creativity and Innovation- Students demonstrate creative thinking, construct knowledge, and develop innovative products and processes using technology.


‚Äʬ†Standard:¬†6. Technology Operations and Concepts- Students demonstrate a sound understanding of technology concepts, systems and operations.


NYSED Math Standards

G.G.20 Construct an equilateral triangle, using a straightedge and compass, and justify the construction


G.G.27 Write a proof arguing from a given hypothesis to a given  conclusion


At the end of this lesson, students will BE ABLE TO:

Math Content

  • Recognize equilateral triangles based on properties
  • Construct equilateral triangles
  • Write a proof of equilateral triangles


  • Use Geometer‚Äôs Sketchpad to construct equilateral triangles
  • Use email to send files.
  • Print off of Geometer‚Äôs Sketchpad
At the end of this lesson, students will KNOW:
Equilateral triangles are composed of 3 sides of equal length.


Equilateral triangles are divided into 3 equal angles with a total sum of 180.



  • Equilateral
  • Angle
  • Side
  • Measure
  • Radius
At the end of this lesson, students will THINK ABOUT:
How can we use Sketchpad to draw isosceles triangles? Right triangles?


What do these triangles have in common?


How can I write a proof of an equilateral triangle?


DO NOW Individually and in their notebooks, students will answer the following questions:


What is an equilateral triangle?

Draw an equilateral triangle in your notebook.


I will be walking around answering questions and assessing who is and is not on task.

MINI-LESSON First, I will show students the rubric from which they will be graded throughout this lesson and share my expectations of them. The mini-lesson here will focus on identifying different types of triangles. I will use the Smartboard to show students one example of each different type of triangle. Then, I will focus on equilateral triangles.
ACTIVITY 1.       After discussing equilateral triangles properties, students will watch a short clip on drawing equilateral triangles projected on the Smartboard.

2.        Next, there will be a small discussion around what skills were put in place to build an equilateral triangle with 3 perfectly equal sides. As a class we will determine the steps needed to construct an equilateral triangle using a compass and straight edge.

3.       Next, we will move onto constructing an equilateral triangle on Geometer’s Sketchpad. Students will work in pairs on a laptop and construct 3 different sized equilateral triangles. Using the software, they will need to take the measure of the segments of each of the triangles, of each of the angles and all vertices must be labeled. They will save their images and the script of the steps they took to draw them and email them to me. Students will also print their images to save for themselves.

4.       We will again come together as a class to discuss processes, difficulties and any general ideas discovered throughout the construction process. Some important ideas for them to share are:

-All sides have equal measure

-All angles are of equal measure

All notes will be taken on Smartboard for students to follow along and copy.

5.        Finally, students will go home with their drawings and notes to help them with their homework.

SUMMARY/ASSESSMENT A quick exit slip will be given to each student that will work as a brief assessment as well as an indicator for what I should focus on in the upcoming lesson.


Exit Slip-3 Quick Questions:

1.       Name all properties of an equilateral triangle.

2.        What did you find interesting or helpful during the lesson in understanding how to construct equilateral triangles?

3.        What are you still unclear about?


I will print out each student’s triangle exercise to include in their math portfolio.


As homework, students will need to prove that one of their triangles is an equilateral triangle. They must use the triangle they constructed, and the notes that they took in class to support and guide their proof. The work must be done on a separate sheet of paper. It does not need to be typed but must be neat and organized.
Students will be asked to email their triangles and construction script to me to assess if their processes are correct. (To be graded)


I will also use the Exit Slips as a quick assessment. (not graded)


Laptops equipped with Geometer’s Sketchpad, Smartboard

Lesson Grading Rubric: Equilateral Triangles


Name/Class: _________________________                                    Date: ____________


Each component of the lesson must be completed in order to receive the full amount of points. A point is given for successfully completing each bullet point under each category. You lose a point for each incomplete bullet point. Each category will include a score from 0 to 3 points and a description of what was done well or not as well and why you received the score you did. If you are unsatisfied with your score in any category, you must bring it to my attention by the end of the same day you received the rubric grade.


Criteria 0 1 2 3


-Completed the Do Now (answered all questions)


-Asked questions/shared an idea for discussion/contributed to ideas with partner on Geometer’s Sketchpad


-Took notes in notebook including vocabulary


Lesson Activity


-Emailed drawing with script


-Triangle is an equilateral triangle with labeled vertices


-Script shows correct construction of equilateral triangle




-Handed in exit slip


-Handed in completed homework


-Homework is accurate and complete




Overall Score: Notes:







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