Topicm5839b1f486a17ef2_1528449000663_0Topic

The tangram

Levelm5839b1f486a17ef2_1528449084556_0Level

Second

Core curriculumm5839b1f486a17ef2_1528449076687_0Core curriculum

IX. Polygons, disks and circles. The student:

1) recognizes and names: acute triangles, right triangles, obtuse triangles, equilateral triangles and isosceles triangles;

5) knows the most important properties of a squaresquaresquare, a rectangle, a rhombus, parallelogramparallelogramparallelogram and a trapezium, recognizes axially symmetric figures and indicates the axis of symmetry of figures.

Timingm5839b1f486a17ef2_1528449068082_0Timing

45 minutes

General objectivem5839b1f486a17ef2_1528449523725_0General objective

Using simple, well‑known mathematical objects, interpretation of mathematical notions and operating with mathematical objects.

Specific objectivesm5839b1f486a17ef2_1528449552113_0Specific objectives

1. Interpretation and the use of information presented both in a mathematical and popular science texts also using graphs, diagrams and tables.

2. Recognizing and naming polygons.

3. Applying the properties of polygons in geometric problems.

Learning outcomesm5839b1f486a17ef2_1528450430307_0Learning outcomes

The student:

- recognizes and names polygons,

- applies the properties of polygons in forming particular geometric figures.

Methodsm5839b1f486a17ef2_1528449534267_0Methods

1. Educational game.

2. Mini‑drama.

Forms of workm5839b1f486a17ef2_1528449514617_0Forms of work

1. Individual work.

2. Group work.

Lesson stages

Introductionm5839b1f486a17ef2_1528450127855_0Introduction

A short test on types of polygons. The students work individually. The teacher shoes cardboard models – first, quadrangles, and later various polygons. The students write down their names (e.g. a trapezium, a squaresquaresquare, a heptagon). Then, the teacher gives correct answers and explains doubts. The students assess themselves.

The teacher informs that polygons have fascinated the scientists for ages. 3000 years ago a puzzlepuzzlepuzzle, called the tangram, was invented in China. It consists of 7 polygons, called tans, which were produced by cutting a squaresquaresquare.

During the class the student will build various geometric figures with the tans.

Procedurem5839b1f486a17ef2_1528446435040_0Procedure

Group work. Each group gets the tangram and specifies what shapes are the elements.

The students should notice that the tangram consists of:

- 5 right triangles,

- A square,

- A parallelogramparallelogramparallelogram.

The teacher shows some examples of figures that may be formed using the tans.

Task 1
Students' task is to arrange figures using all the tan. First, observe the character you want to form carefully, then prepare the strategy and eventually create it.

[Geogebra applet]

Task 2
Working in small groups. The students get the tangrams made of adhesive paper. They use some diagrams showing figures that can be formed with the tans and assemble some of the figures. They may also invent their own polygons. They stick their figures onto the cardboard.

The students invent a story and use mini‑drama technique to act out a scene. They act using the figures. They can invent any plot, but they have to use the properties of the polygons that they have formed.

“The audience” chooses the best story – one of the criteria is the correct and appropriate use of the properties of polygons (e.g. the measure of their angles, the position of the side in relation to one another).

An extra task:
Use 14 elements of an old Greek puzzlepuzzlepuzzle called ostomachion to assemble a squaresquaresquare.

Lesson summarym5839b1f486a17ef2_1528450119332_0Lesson summary

The students do the consolidation tasks.

Next, they summarize the class and formulate the conclusions that they should remember.

- The tangram is an old Chinese puzzle, consisting of 7 elements, called tans, which were produced by cutting a square.m5839b1f486a17ef2_1527752256679_0The tangram is an old Chinese puzzle, consisting of 7 elements, called tans, which were produced by cutting a square.

- It is possible to form various geometric figures with the tans.m5839b1f486a17ef2_1527752263647_0It is possible to form various geometric figures with the tans.

Selected words and expressions used in the lesson plan

elementelementelement

parallelogramparallelogramparallelogram

polygonpolygonpolygon

puzzlepuzzlepuzzle

right triangleright triangleright triangle

squaresquaresquare