Measuring angles – Grade 4 math lesson
Lesson 24 of 26 in the Grade 4 math course
US version. US grades, US spelling and dollars ($). · UK Maths Department
A complete 45-minute lesson for grade 4 (ages 9–10) that runs on this page – at school or at home. Every answer is graded right away, with a worked explanation.
- Time
- 45 minutes + 20 min homework
- Grade
- Grade 4 (ages 9–10)
- You need
- Paper, a pencil and this page
- Graded
- Instantly, with explanations
For parents: how to use this lesson
You don't need to know this topic yourself. The lesson explains each step on screen, one tidy step at a time. Every answer is graded straight away with a worked explanation, so you never have to grade anything.
- Read what your child will learn and the big ideas together.
- Press Start the lesson below and sit with your child for the teaching and the worked examples (about 19 minutes).
- Let them do the practice on their own. They choose Getting started, On track or Challenge – start on On track and move up after a few right in a row.
- Finish with the exit ticket and the talk question: “How can you tell which scale on the protractor to read?”
- Later that day or the next day: the homework (20 minutes), then a practice test.
Watch out for
- Reading the wrong scale on the protractor (giving 130° for 50°). Check: is the angle acute or obtuse? Then pick the matching number.
- Thinking longer arms make a bigger angle. The angle is the turn, not the length of the lines.
Tip for home: Look for right angles, acute and obtuse angles around the house.
What your child will learn
Learning goal: recognize acute, obtuse and right angles and measure angles with a protractor.
Success looks like
- I can name types of angle.
- I can estimate an angle.
- I can measure an angle with a protractor.
Key words
- angle
- an amount of turn, measured in degrees (°)
- acute
- less than 90°
- obtuse
- between 90° and 180°
- protractor
- a tool for measuring angles
What to have ready
- Paper and a pencil
- This page on a computer, tablet or phone
- For the hands-on part: Make angles with two strips of card joined by a split pin, and sort them into acute, right and obtuse. No protractors? Use two pencils to make angles and a corner of paper as a right angle.
The big ideas (for the adult)
An angle is an amount of turn. A right angle is a quarter turn, 90°.
An acute angle is less than 90°, an obtuse angle is between 90° and 180°, and a reflex angle is more than 180°.
To measure with a protractor, put the center on the vertex and the zero line along one arm, then read the scale that starts at 0.
The lesson, step by step
| Part | Time | How it is checked |
|---|---|---|
| Starter: quick recall | 5 min | Graded by Classfern |
| Teaching input | 10 min | Not assessed, self-checked |
| Worked examples and guided practice | 9 min | Not assessed, graded by Classfern |
| Independent practice | 15 min | Graded by Classfern |
| Closure and exit ticket | 6 min | Graded by Classfern, self-checked |
Starter, "your turn", practice and exit ticket are graded by Classfern. Worked examples and teaching are not assessed. The hands-on task and the reflection are self-assessed. Explanations in talk are judged by the parent and not recorded.
The lesson
It runs here on the page. No sign-up and no names – progress is kept only in this browser.
Homework and practice at home
20 minutes: 10 practice questions, 3 multiple-choice questions and 2 to remember from earlier work, then a short reflection. New questions every time, all graded instantly.
More practice
More Grade 4 math lessons
- Factors and multiples
- Prime and composite numbers
- Multiplication and division
- Solving word problems
- Number patterns
- Place value: the value of each digit
- Rounding to the nearest 10, 100 or 1,000
- Adding with the standard algorithm
- Subtracting with the standard algorithm
- Decimals: tenths, hundredths and thousandths
- Comparing, ordering and writing numbers
- Equivalent fractions
- Adding and subtracting fractions with like denominators
- Fractions of a whole number
- Comparing and simplifying fractions
- Fractions, decimals and percentages
- Area of rectangles
- Perimeter
- Finding unknown angles
- Converting units of time
- Line plots
- Converting measurement units
- Classifying 2-D shapes
- Lines of symmetry
Curriculum
Common Core State Standards 4.G.A.1: “Draw points, lines, line segments, rays, angles (right, acute, obtuse), and perpendicular and parallel lines. Identify these in two-dimensional figures.”
Common Core State Standards 4.MD.C.5.a: “An angle is measured with reference to a circle with its center at the common endpoint of the rays, by considering the fraction of the circular arc between the points where the two rays intersect the circle. An angle that turns through 1/360 of a circle is called a "one-degree angle," and can be used to measure angles.”
Our lessons and questions are our own. They are not written or endorsed by any government department, testing agency or exam board.