Describing Angles & Lines

We're cruising right along in Geometry!

Angles are made when lines, rays, or line segments intersect.

This week, we will learn how to describe angles by comparing them to right angles, which are easy to identify because they form a square corner, like the corner of a paper.

Acute angles are less than (or narrower than) right angles.  If you can't fit the corner of a paper inside an angle, then it's acute.

Obtuse angles are greater than (or wider than) right angles.  If you can fit the corner of a paper inside an angle and there's still space that isn't covered, then it's an obtuse angle.

We will also learn to describe lines, rays, and line segments that are perpendicular or parallel.

I like to use two straight sides of papers (or two rulers) to extend lines, so it's easier to see if they will ever intersect.  Remember, if they never intersect, then they are parallel!

How would  you describe the fins on this surfboard?

Would you say the design on this board is perpendicular to the stringer?  Why or why not?

Points, Lines, Rays, and Angles

So many new things upstairs!  As we take in a new school year, this week we are starting Math with Geometry since it's all about observing and describing shapes!

As a third grader, your student's goal was to understand that shapes in different categories (e.g., rhombuses, rectangles, and others) may share attributes (e.g., having four sides), and that the shared attributes can define a larger category (e.g., quadrilaterals).  Your student should be able to recognize rhombuses, rectangles, and squares as examples of quadrilaterals, and draw examples of quadrilaterals that do not belong to any of these subcategories. (Need a refresher?  Check out this Study Jam: Classify Quadrilaterals .)

What do you notice about this swell?  How would you describe the waves?

Fourth graders must be able to draw points, lines, line segments, rays, angles (right, acute, obtuse), and perpendicular and parallel lines. Students must also identify these in two-dimensional figures.

Check out this Study Jam on Types of Lines. (Make sure you listen to/sing the karaoke song!)

Here's a Khan Academy video to introduce/review right, acute, and obtuse angles.

Look around the room where you are.  Do you see any of these figures around you?  Soon you'll start seeing them everywhere!  :-)