Topicmfb8f0af60ef7b0e5_1528449000663_0Topic

Revision on plane figures

Levelmfb8f0af60ef7b0e5_1528449084556_0Level

Second

Core curriculummfb8f0af60ef7b0e5_1528449076687_0Core curriculum

VII. Lines and Line segments. The student:
1) Recognizes and names figures: a pointpointpoint, a line a rayrayray, a line segmentline segmentline segment.

IX. Polygons, disks and circles. The student:
6) indicates a chord, a diameter and a radius of a disk and a circle in the diagram.

Timingmfb8f0af60ef7b0e5_1528449068082_0Timing

45 minutes

General objectivemfb8f0af60ef7b0e5_1528449523725_0General objective

Using simple, well‑known, mathematical objects, interpreting mathematical concepts and operating mathematical objects.

Specific objectivesmfb8f0af60ef7b0e5_1528449552113_0Specific objectives

1. Communication in English, developing mathematical, IT and basic scientific and technical competence, developing learning skills.

2. Revision of concepts connected with basic geometric figures.

3. Recognizing basic geometric figures and applying their properties.

Learning outcomesmfb8f0af60ef7b0e5_1528450430307_0Learning outcomes

The student:

- revises the concepts connected with basic geometric figures,

- recognizes and draws basic geometric figures, applies their properties.

Methodsmfb8f0af60ef7b0e5_1528449534267_0Methods

1. Wandering cards.

2. Working with an expert.

Forms of workmfb8f0af60ef7b0e5_1528449514617_0Forms of work

1. Whole class.

2. Group work.

Lesson stages

Introductionmfb8f0af60ef7b0e5_1528450127855_0Introduction

The teacher informs the students that the aim of the class will be revision on plane figures.

The students sit in a circle, in the middle of which there is an empty box. Using the “wandering cards” technique the students revise their information about plane figures.

The first student draws one of plane figures, e.g. a line segmentline segmentline segment, on a piece of paper and passes it to another student. The student writes the name of the figure and puts the paper into the box. In the meantime, the first student says aloud what figure he/she has drawn. The second student draws another figure on another blank sheet of paper and passes it to another student. The whole procedure is repeated until there are no more ideas of figures.

Then, a volunteer takes a sheet of paper out of the box and checks if the diagram has appropriate name on it. If not, he / she shows the paper to other students and asks them to give the correct name of the figure.

Proceduremfb8f0af60ef7b0e5_1528446435040_0Procedure

The students watch an interactive presentation which systematizes the concepts connected with plane figures.

[Slideshow]

Then, the students work in small groups. Each group’s aim is to solve one of the tasks and invent another, similar task. In this way, the members of the group become the experts on a given problem. After the time limit defined by the teacher, the groups discuss the solution to their task with the whole class. They answer any questions and ask other groups to solve the task they have invented.

Task for group 1
Complete the sentences:

a. Every geometrical figure consists of …
b. A line consists of … points.
c. … on a line define a line segments.
d. A pointpointpoint divides a line into two …

Task for group 2
Decide if a given angle is acute, right or obtuse:

a. an angle which is made by two diagonals of a deltoid,
b. an angle between two adjacent sides of a rectanglerectanglerectangle,
c. an interior angle of an equilateral triangletriangletriangle,
d. an angle whose arms overlap.

Task for group 3
Draw:

a. three straight lines intersecting in three points,
b. two parallel line segments,
c. rays intersecting at an angle of 45°,
d. two perpendicular lines.

Task for group 4
[Illustration]

a. Angle α is three times larger than angle β. Find the measures of angles γ and δ.
b. Angle γ measures 103°. Find the measures of the other angles.
c. Indicate pairs of vertical angles in the diagram.
d. Indicate pairs of adjacent angles in the diagram.

Task for group 5
Decide in which:

a. polygonpolygonpolygon the sum of angles measures 180°,
b. quadranglequadranglequadrangle the diagonals intersect at the right angle,
c. polygonpolygonpolygon there are only two diagonals,
d. quadranglequadranglequadrangle the sum of angles at one side equals 180°.

Task for group 6
Complete the sentences:

a. If one chord of a circle has the length of 8 cm, the diameter of this circle has the length … 8 cm.
b. In a circle whose radius is 3 cm, the longest chord is … long.
c. If the diameter of a circle equals 5, the radius of this circle equals …
d. The centre of the disk … to this disk, but the centre of the circle … o this circle.

The teacher assesses the “experts”’ work and explains any doubts.

An extra task:
What is the maximum number of intersection points of 3 lines? And 4 lines? And 5 lines?

Lesson summarymfb8f0af60ef7b0e5_1528450119332_0Lesson summary

The students do the consolidation tasks.

They cooperate to summarize the class and formulate the conclusions to memorize:

- Every geometrical figure consist of points.
- The angles in (convex) polygons are right, acute or obtuse.
- Two intersecting lines form two pairs of vertical angles and four pairs of adjacent angles.
- The sum, of angles in a triangle equals 180° and in a quadrangle equals 360°.mfb8f0af60ef7b0e5_1527752263647_0The sum, of angles in a triangle equals 180° and in a quadrangle equals 360°.
- The diameter of a circle is twice as big as the radius of this circle.mfb8f0af60ef7b0e5_1527752256679_0The diameter of a circle is twice as big as the radius of this circle.

Selected words and expressions used in the lesson plan

line segmentline segmentline segment

pointpointpoint

polygonpolygonpolygon

quadranglequadranglequadrangle

rayrayray

rectanglerectanglerectangle

squaresquaresquare

straight linestraight linestraight line

triangletriangletriangle