4th Grade · Geometry
4.G.A.1: Name rays and angles, and spot parallel and perpendicular lines
4.G.A.1 is a 4th grade Common Core math standard in Geometry. Here’s what it really covers, and how you can help your students learn it.
By Robert “Bobby” BarnettMath teacher, parent, and founder of Bobby’s Math Club
The standard
Draw points, lines, line segments, rays, angles (right, acute, obtuse), and perpendicular and parallel lines. Identify these in two-dimensional figures.
In plain words
Name rays and angles, and spot parallel and perpendicular lines.
Sample questions from student practice
These questions from Bobby's Math Club are the kinds of questions your students will see. You can try answering them to see what a student might see.
Question 1 of 3
How many endpoints does a line segment have?
- Two
- One
- Zero
Where students can get stuck
- Mixing up lines, rays, and segments, such as calling a segment with two endpoints a line.
- Calling an angle obtuse because its rays are long, or acute because they are short, instead of checking how wide it opens.
- Thinking perpendicular lines must run straight up and across, and missing them when they are tilted on the page.
Effective teaching strategies
- Draw a segment, a ray, and a line, and have students tell how they differ, noting endpoints and that arrows mean the line goes on forever in both directions.
- Fold a sheet of paper to make a square corner and use it to check whether each angle is less than, equal to, or greater than a right angle.
- Have students find parallel and perpendicular lines in tilted figures by turning the page, looking for lines that meet at a square corner or never meet.
Units that teach this standard
Find where 4.G.A.1 lands in the program you teach. Each unit has a guide written for families. Unit names and order vary between editions and districts, so your school’s own materials have the exact sequence.
Bridges in Mathematics
enVision Mathematics
Everyday Mathematics
i-Ready Classroom Mathematics
Illustrative Mathematics
Math Expressions
Reveal Math
Don’t see your curriculum? Contact Bobby and we’ll see if we can help!
Share it with families
Families can read Spotting lines, rays, angles, and parallel lines for a plain-language look at this skill, with three questions to try together and ideas for helping at home.
Help every student practice geometry at home
In Bobby's Math Club, students practice at just the right level, with a hint when they need one, a clear explanation after every question, and kid-friendly videos. Unlimited practice is free for every family.
See how it works for teachers
Written by Robert “Bobby” Barnett
Bobby is an award-winning math teacher, the author of Meet Every Learner’s Needs, and the father of two elementary-school math learners. He uses Bobby’s Math Club with his own kids a few times every week. Learn more or contact Bobby.