Triangle Inequality Lesson with Socrative
Unit: 2- The Language and Logic of Geometry
Lesson Essential Question (LEQ): How do I determine whether or not three side lengths can create a triangle?
Assessment Prompts (What students must know to be able to answer the LEQ):
AP#1: Students must be able to use the triangle inequality postulate to determine whether or not three side lengths can create a triangle.
AP#2: Given two sides lengths, students must be able to determine the possible values of the third side.
Visualize and represent geometric figures and describe the relationships between them.
Verify and apply geometric theorems as they relate to geometric figures.
Apply inverse operations to solve equations or formulas for a given variable.
Materials: 2.7 Flipchart, Lesson Master 2.7A, bag of straws with appropriate lengths and colors as per the activity chart (1 pack per group), Activity sheet (1 per student), student iPads with Evernote, Socrative, and Show Me applications
THINK-PAIR-SHARE: Students will work independently for approximately 2 minutes to solve the bell-ringer. They will discuss their answers with their partners for about 30 seconds and explain their reasoning (use drawings), and we will then share our results as a class.
Key Vocabulary: Triangle Inequality Postulate
Group Discovery Activity:
1) Students will work in randomly selected groups of 3-4. Students should join their group and find a place to work somewhere around the room (will need a flat surface to work on).
2) Each group will be given a bag of straws. Each straw is a different length and color (see corresponding chart). As a group, students will complete the data chart by using the straws as manipulatives to determine whether or not the given side lengths in the first column will create a triangle. Students will fill out the chart using the Show Me App by taking a picture of the chart on the board with their iPads, uploading it to Show Me, filling it out, then screenshot to add into Evernote. If students finish early, they may try additional combinations of side lengths in the blank rows of their data sheet.
Below is a photo of what I display on the board for the activity and also the data sheet.
3) After trying each of the side combinations and determining whether or not a triangle can be made, student groups will analyze and discuss any patterns or relationships they notice between the side lengths that worked and did not work. A class discussion will follow once all groups have made a conclusion.
We will then come back together as whole class to take notes on the Triangle Inequality Postulate via the Evernote App. Students will download the note taking guide and fill in the blanks from my presentation on the Promethean Board.
Extended Thinking Strategy:
Group Challenge: Suppose we have two side lengths of a triangle- 32 feet and 45 feet. Write an inequality that describes possible lengths for the third side (HINT: use your inequality formulas given by the Triangle Inequality Postulate!).
Student groups will play the Space Race game in Socrative to check for understanding of the Triangle Inequality Postulate. Students will answer seven multiple choice questions that give three sides lengths and they must determine whether or not they would make a triangle (this time without manipulatives).
2.8- Read, KWL, & CTR questions