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Classifying Triangles Sides & Angles Guided Notes w Doodles | 5th Grade Geometry
$4.25
Overview
Ever wondered how to teach classifying triangles by sides and angles in an engaging way to your 5th-grade students? In this lesson plan, students will learn about how to classify triangles by sides (equilateral, isosceles, scalene) as well as classify triangles by angles (acute, obtuse, right). Through artistic, interactive guided notes, check for understanding, practice coloring worksheet, and a maze, students will gain a comprehensive understanding of triangle classification. Students will be given examples of each type of triangles as well as triangles that may fall into multiple category (i.e. an isosceles acute triangle).
The lesson ends with a real-life example that explores how understanding the properties of triangles can be applied in everyday scenarios. Students will read and write about the real-life uses of classifying triangles, connecting their learning to practical situations.
- Standard: CCSS 5.G.B.4
- Unit: 5th Grade → Unit 6: 2D Geometry
- Grade: 5th Grade
Get the Lesson Materials
Classifying Triangles Sides & Angles Guided Notes w Doodles | 5th Grade Geometry
$4.25
Learning Objectives
After this lesson, students will be able to:
Classify triangles based on the lengths of their sides as equilateral, isosceles, or scalene.
Classify triangles based on the measures of their angles as acute, obtuse, or right.
Identify and apply the properties of different types of triangles when given examples.
Analyze real-life scenarios and explain how the classification of triangles by sides and angles can be useful in practical situations.
Prerequisites
Before this lesson, students should be familiar with:
Knowledge of basic geometric shapes (triangles, squares, rectangles, circles)
Materials
Pencils
Colored pencils or markers
Classifying Triangles Sides & Angles Guided Notes with Doodles
Key Vocabulary
Triangles
Equilateral
Isosceles
Scalene
Acute
Obtuse
Right
Procedure
Introduction
As a hook, ask students why understanding the different types of triangles might be useful in real life situations. Refer to the last page of the guided notes titled "Real-life application" for ideas on how to link triangle classification to practical scenarios.
Use the first page of the guided notes to introduce the concept of classifying triangles by their sides (equilateral, isosceles, scalene triangles). Walk through the definitions of each type of triangle, emphasizing the key characteristics that differentiate them. Refer to the FAQ below for a walk-through on this topic, as well as ideas on how to respond to common student questions.
Proceed to use the second page of the guided notes to introduce classifying triangles by their angles (acute, obtuse, right triangles). Explain the definitions of each type of triangle based on angle measurements, highlighting how to identify them visually. Refer to the FAQ below for guidance on teaching this section effectively and addressing any student inquiries.
Based on the students' responses during the introduction and initial explanation, reteach any concepts that students may need additional help understanding. If there is a wide range of proficiency levels in the class, consider pulling out students for reteaching while more advanced students begin working on the upcoming practice exercises.
Practice
Have students practice classifying triangles by sides and angles using the practice worksheet included in the resource. Students can start with the maze activity (pg. 3 of guided notes) to practice classifying triangles to escape the maze. Walk around to answer student questions.
Then, fast finishers can start the color by code activity (pg. 4 of guided notes) for extra practice. You can assign it as homework for the remainder of the class.
Real-Life Application
Using the last page of the guided notes, bring the class back together, and introduce the concept of using triangles in architecture and construction. Triangles are essential in constructing stable and sturdy structures like bridges, buildings, and even roller coasters. Discuss with students how architects and engineers use their knowledge of different types of triangles to design and build safe and reliable structures. Students will read about the real life applications and reflect on a short prompt as well as complete a self assessment on their confidence level on this math topic.
Refer to the FAQ for more ideas on how to teach it!
Extensions
Additional Self-Checking Digital Practice
If you're looking for digital practice for Classifying Triangles by Angles & Sides, try my Pixel Art activities in Google Sheets. Every answer is automatically checked, and correct answers unlock parts of a mystery picture. It’s incredibly fun and a powerful tool for differentiation.
Here is an activity to explore:
Additional Print Practice
A fun, no-prep way to practice Classifying Triangles by Angles & Sides is Doodle Math — they’re a fresh take on color by number or color by code. It includes multiple levels of practice, perfect for a review day or sub plan.
Here are 1 activity to try:
FAQs
There are three main types of triangles based on their angles:
Acute Triangle: All angles are less than 90 degrees.
Obtuse Triangle: One angle is greater than 90 degrees.
Right Triangle: One angle is exactly 90 degrees.
Triangles can be classified into three categories based on their sides:
Equilateral Triangle: All three sides are of equal length.
Isosceles Triangle: Two sides are of equal length.
Scalene Triangle: No sides are of equal length.
The sum of the three angles in any triangle is always 180 degrees.
An equilateral triangle has three equal sides and three equal angles, each measuring 60 degrees.
A triangle is classified as obtuse if one of its angles measures more than 90 degrees.
Isosceles triangles have two sides of equal length and two equal angles, while scalene triangles have all sides of different lengths and no equal angles.
No, a triangle cannot be both acute and equilateral because an equilateral triangle has all angles measuring 60 degrees, which are acute angles.
A right triangle has one angle that measures exactly 90 degrees.