Topicm2079461d21820e54_1528449000663_0Topic

Angles and their types

Levelm2079461d21820e54_1528449084556_0Level

Second

Core curriculumm2079461d21820e54_1528449076687_0Core curriculum

VIII. Angles.

The student

1. identifies the legs and the vertex in every angleangleangle

3. draws angles smaller than 180°;

4. recognises the following angles: acute, obtuse and right.

Timingm2079461d21820e54_1528449068082_0Timing

45 minutes

General objectivem2079461d21820e54_1528449523725_0General objective

Using mathematical objects, interpreting mathematical concepts.

Specific objectivesm2079461d21820e54_1528449552113_0Specific objectives

1. Identifying the following angles: right, acute, obtuse, straight and full.

2. Drawing the following angles: right, acute, obtuse, straight and full.

3. Communicating in English, developing basic mathematical, computer and scientific competences, developing learning skills.

Learning outcomesm2079461d21820e54_1528450430307_0Learning outcomes

The Student:

- identifies different types of angles,

- draws the following angles: right, acute, obtuse, straight and full.

Methodsm2079461d21820e54_1528449534267_0Methods

1. Situational analysis.

2. Brainstorming.

Forms of workm2079461d21820e54_1528449514617_0Forms of work

1. Individual work.

2. Group work.

Lesson stages

Introductionm2079461d21820e54_1528450127855_0Introduction

The teacher introduced the subject of the lesson: the concept of an angleangleangle and the basic types of angles.

On basis the colloquial meaning of the word ‘angleangleangle’ Students point out the models of angles in the surrounding reality.

[Illustration 1]

Procedurem2079461d21820e54_1528446435040_0Procedure

Task 1

Students draw a few angles in their notebooks. They discuss the similarities and differences. Then, through brainstorming and with the teacher’s help they formulate the definition of the angleangleangle.

Definition:
An angle is a part of the plane, marked by two rays which have a common beginning, together with these rays. The rays mark two angles. The rays are called the legs of the angle and their common beginning in the vertex of the angle.m2079461d21820e54_1527752263647_0An angle is a part of the plane, marked by two rays which have a common beginning, together with these rays. The rays mark two angles. The rays are called the legs of the angle and their common beginning in the vertex of the angle.

[Illustration 2]

Task 2

Students fold a piece of paper in any place. Then they fold it again in such a way that the lines of the first folding are covered. They obtain a model of an angle which they compare with the greatest angle of the set square.

[Illustration 3]

Task 3

The teacher gives students the names of various types of angles (acute, right, obtuse, straight and full) and presents them in drawings. The teacher draws a few different angles on the board. Students match the names with the appropriate angles.

Conclusions that students should draw:

- a straight angle is an angleangleangle whose legs form a line,
- a full anglefull anglefull angle is an angle whose legs overlap,
- an acute angleacute angleacute angle is an angle smaller than the right angleright angleright angle,
- an obtuse angleobtuse angleobtuse angle is an angle smaller than the straight angle and greater than the right angle.

Task 4

Students draw two examples of each of the following angles: acute, right, obtuse, straight and full.
They name each of them.

Task 5

Students work individually, using computers. Their task is to identify the type of the angle.

[Geogebra aplet 1]

An extra task:

Identify the angleangleangle (acute, right, obtuse, straight or full) that the minute hand of the clock forms between
the following times:
a) 5.12, and 5.20
b) 4.30, and 5.00
c) 3.15, and 3.40
d) 1.20, and 1.35

Lesson summarym2079461d21820e54_1528450119332_0Lesson summary

Students do the revision exercises. Then together they sum‑up the classes, by formulating the conclusions to memorise:

An angleangleangle is a part of the planeplaneplane, marked by two rays that have a common beginning, together with these rays. The rays mark two angles. The rays are called the legs of the angle and their common beginning in the vertex of the anglevertex of the anglevertex of the angle,
There are different types of angles: acute, right, obtuse, straight and full,
- a right angle is the greatest angle of a setsquare,
- an acute angle is an angle smaller than the right angle,
- an obtuse angle is an angle smaller than the straight angle and greater than the right angle,
- a straight angle is an angle whose legs form a line,
- a full angle is an angle whose legs overlap.m2079461d21820e54_1527752256679_0There are different types of angles: acute, right, obtuse, straight and full,
- a right angle is the greatest angle of a setsquare,
- an acute angle is an angle smaller than the right angle,
- an obtuse angle is an angle smaller than the straight angle and greater than the right angle,
- a straight angle is an angle whose legs form a line,
- a full angle is an angle whose legs overlap.

Selected words and expressions used in the lesson plan

acute angleacute angleacute angle

angleangleangle

full anglefull anglefull angle

leg of the angleleg of the angleleg of the angle

obtuse angleobtuse angleobtuse angle

planeplaneplane

rayrayray

right angleright angleright angle

straigh anglestraigh anglestraigh angle

vertex of the anglevertex of the anglevertex of the angle