DMS · School Lab · Teacher card
Angle Gate
The big question: What makes an angle bigger: the length of its arms or how far it turns?
Goal: Children compare angles by how far they turn rather than by arm length, and identify acute, right, obtuse and straight angles against a right angle.
In the lesson
Lesson flow
| Step | What children do | min |
|---|---|---|
| 1 · Ready? | Meets the hinged door, the robot arm and the set square. | ≤ 1 |
| 2 · What do I know? | Shows which is bigger: a wide angle with short arms or a narrow angle with long arms. | 1 |
| 3 · In everyday life | Thinks about door hinges, scissors, clock hands and elbows. | 1 |
| 4 · Predict | Predicts whether the angle grows when the arms get longer; the prediction is locked in. | 1–2 |
| 5 · Try and observe | The arms grow but the angle reading stays the same; the flashlight beam just reaches further. | 2–5 |
| 6 · Why? | Sees that an angle is an amount of turn; uses the right angle as a reference and learns ray, vertex and the angle symbol. | 2–4 |
| 7 · Try something new | Measures with a protractor, draws an angle of a given size and sorts acute, right and obtuse angles with a set square. | 2–6 |
| 8 · My explorer notebook | Picks the door that has turned the most out of three with different arm lengths. | 1–3 |
| Off-screen activity, discussion and wrap-up | ≈ 15 | |
Class prediction vote
If we make the door's arms longer, does the angle get bigger?
Discussion questions
- The arms got longer, so why did the angle stay the same?
- What if we opened the door a bit more?
- How can we tell an angle is bigger than a right angle?
Avoid saying: “The angle with longer arms is bigger.”
Say instead: “An angle is about how far it turns; longer arms don't change it.”
Off-screen activity for the teacher's desk: Turning arms
Pupils start with their arms together, then open them as far as you say: less than a right angle, a right angle, more than a right angle. Then hold two pencils on the teacher's desk at the same angle and swap them for longer ones.
You need: Two long and two short pencils or rulers · A set square
Details
Grades and learning outcomes
- Grade 4: M.4.2.3.2 (2018 curriculum), M.4.2.3.3 (2018 curriculum), M.4.2.3.4 (2018 curriculum), M.4.2.3.5 (2018 curriculum) · Equivalent from 2027–28: MAT.4.3.5, MAT.4.3.6, MAT.4.3.7
Scope
The Maarif Model version (from 2027–28) has no protractor measuring and no straight angle; in 2026–27 this lab follows the 2018 curriculum.
Misconceptions
- “The angle with longer arms is bigger.” → The arms grow but the angle reading doesn't change; the arms just reach further.
- Thinking only right angles are angles. → The door makes an angle in every position; acute and obtuse angles are compared with a right angle using the set square.
Getting ready
- Open the lab on the board; grade 4 is selected.
- For the screen-free activity: two long and two short pencils or rulers and a set square.
- Angle numbers are large on the board; check they can be read from the back row.
This lab is mapped to learning outcomes M.4.2.3.2, M.4.2.3.3, M.4.2.3.4 and M.4.2.3.5 of the Turkish Ministry of National Education's 2018 Mathematics curriculum. It has not been reviewed or approved by the Ministry of National Education (MEB) or its Board of Education (TTKB).
From the 2027–28 school year, the grade 4 equivalent in the Türkiye Century Maarif Model is MAT.4.3.5, MAT.4.3.6 and MAT.4.3.7.