Videos and lessons to help Grade 4 students learn to classify two-dimensional figures based on the presence or absence of parallel or perpendicular lines, or the presence or absence of angles of a specified size. Recognize right triangles as a category, and identify right triangles.

Common Core: 4.G.2

### Suggested Learning Targets

• I can classify two-dimensional shapes into categories (including those with/without parallel line segments and perpendicular line segments)
• I can classify shapes by its angles.
• I can identify a right triangle.

Related Topics:

Identifying Properties of Lines and Angles 4.G.2
In this video, students will learn to identify shapes using properties of lines and angles. This video relates to Common Core Standard 4.G.2. Students learn to identify right angles, parallel sides, obtuse and acute angles.

Types of Triangles - according to side length
Equilateral, Isosceles, Scalene.

The Three Types of Triangles (Based on What Kinds of Angles They Have)
right triangles, acute triangles, and obtuse triangles!

All the different types of Triangle.

Classifying Triangles
In this video, we discover the six ways to classify trangles, both based on the measure of their side lengths and by the measure of their angles.

The following activities are obtained from the Howard County Public School System.

Activity 1:

Look at the figures below.

Classify the figures based on whether they have any sides that are parallel.  In the left column of the chart, write the number of each shape that has at least one pair of parallel sides.  In the right column, write the number of each shape that has no pairs of parallel sides.

 at least one pair of parallel sides no pairs of parallel sides

What is a different way that the seven figures could be sorted?    Fill in the chart below with two titles to name a different way the figures could be classified.  Then, write the number of each figure in the chart to show the group in which each figure belongs.

Activity 2:

Look at the pentagon marked 1.  Which of the phrases listed below correctly describe that figure?  Check all that apply.

_____  at least one acute angle

_____  at least one obtuse angle

_____ at least one right angle

_____ at least one pair of parallel sides

_____ at least one pair of perpendicular sides

Ian’s teacher gave him the six pentagons shown and asked him to classify them.  He put figures 1, 2, and 6 in group A and figures 3, 4, and 5 in group B.    Describe how the figures in Group A are different from the figures in Group B.

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