The whole class participates in the game. All students face the teacher.

Step 1: The teacher says circle and students raise their hands up and make a big circle above their heads.

Step 2: The teacher says triangle and students make a "roof" over their heads in the shape of a triangle.

Step 3: The teacher gradually increases the tempo and repeats randomly the two words circle and triangle. Anyone who does not make the named figure is out of the game. The activity continues until there are only 2 or 3 children left playing, or until the teacher decides to end the activity.

Students work in pairs to draw a triangle to represent their friendship. Before starting the work, the teacher demonstrates the steps with one of the children. The two persons in the pair place their hands down with the palms facing the surface of the paper sheet; student 1 uses his/her right hand, and student 2 uses his/her left hand.  They join the tips of the thumbs and the forefingers of the left hand of one of the pair with the tips of their thumbs and forefingers and outline the shape of the triangle between the fingers. After that, they can draw eyes, a nose, a mouth and whatever they want to, in order to design a personal symbol of their relationship.

Students will:

• develop skills for recognizing the types of triangles based to the lengths of their sides;
• name the elements of the triangle, including the legs and the base of an isosceles triangle;
• improve their skills of measuring the sides of a triangle and finding its perimeter;
• consolidate their knowledge and skills of adding named numbers (with the centimeter unit of measurement);
• develop a positive attitude towards mathematics;
• gain confidence in their capabilities;
•  see the connection between mathematics and situations from their everyday life.

Materials

Markers/crayons/paints/colored pencils

Black pencil

Ruler/triangle

Scissors

Cardboard boxes with a traffic light for the Reflection activity

A4 sheets of paper

A3 sheets of paper

Equipment

Laptop and projector

Preparation prior to the lesson

1. Prepare one blank A4 sheet for each desk/table.

2. Make color copies of Handout 1 for each desk/table

3. Make colored copies of Handout 2 and cut the 3 triangles separately. Each student should receive one triangle. Therefore, make sure that the number of triangles from the printed sheets is enough for all the students in the class.

4. Prepare the presentation from Annex 3 for demonstration.

5. Make color copies of Handout 4 for each student.

6. Make copies of Handout 5 for each student.

7. Make copies of Handout 6 for each group.

8. Print Handout 7, cut out the traffic lights separately and hand out one image of traffic lights to each student.

Look around. You can find many square-, rectangle-, circle- and triangle-shaped objects. Have you paid attention to the shape of the traffic sign at the zebra crossing? Triangle-shaped, of course. Other traffic signs have the same shape too. The triangle is similar in shape to a piece of your favorite pizza, to a clothes hanger, to the outline of some roofs and to many other objects that we don't even pay attention to. However, if you look closely, you will notice that although they are triangular in shape, these objects are different. In this lesson, we will learn about the different types of triangles considering the lengths of their sides.

Using manipulatives and visualization

Learning in small steps

Group work

Arts - creating a picture recreating a scene from students' everyday life

Mother tongue - skills of expression

The steps in the lesson are comprehensible to most students with special needs who have well-preserved cognitive abilities. The text and instructions of the tasks are short and clear. The role of the support teacher is to help students if they don’t understand the instructions.

Equilateral triangle, isosceles triangle, scalene triangle, leg of an isosceles triangle, base of an isosceles triangle.

Step 1

The lesson begins by updating students' knowledge of the geometric shape triangle and their recognition skills. For this purpose, use the picture with geometric shapes from Handout 1. Distribute one handout to each desk/table. Ask the students to look at the shapes; they have to find and circle only the triangles. Then ask them some questions related to the geometric shape triangle, for example: "How many sides does a triangle have?", "How many vertices does a triangle have?", "Are the sides of a triangle points or line segments?", “Are the vertices of the triangle points or line segments?” (4 min.)

Step 2

Distribute one triangle from Handout 2 to students for individual work. Ask them to measure the lengths of the sides of the triangle they have received using a ruler and record the results of the measurements in the appropriate places. Demonstrate the correct way of using a ruler when measuring the length of a segment. (3 min)

Step 3

Play the presentation (Annex 3). Ask the students who were supposed to measure the sides of the green triangle to stand up. Summarize with suitable questions that the sides of this triangle have equal length. Introduce the term equilateral triangle (slide 2). Then ask all students who worked with the blue triangle to stand up. In this case only two of the sides of the triangle had equal length. Introduce the terms isosceles triangle, lges and base of an isosceles triangle (slide 3). Finally, the students who measured the sides of the red triangle stand up. Ask students to compare the lengths of the sides of this triangle (all different) and introduce the term scalene triangle (slide 4). Sum up the three types of triangles based on the lengths of their sides (slide 5). (5 min)

Step 4

Each student receives a copy of Handout 4.

• Task 1 students have to connect the red dots in the box on the right to make a triangle. Then, they have to measure the lengths of the sides of the triangle, determine its type based on its side lengths, and find its perimeter. Explain that regardless of the type of triangle, its perimeter is the sum of the lengths of its sides. Then, they have look at the other triangles and identify the ones that are the same type as the triangle they have drawn in the box. When they identify them, they have to circle them, count how many they are and write the number in the box under “Number:”.

Check the answers as a whole class activity. (10 min)

Step 5

Distribute Handout 5 to each student.

In Task 1, students have to determine the type of triangles according to the lengths of their sides.

Task 2 is linked to the elements of an isosceles triangle. It is necessary to determine which two sides of the triangle are equal and which side is different in length.

In Task 3, students measure the sides of the triangles, determine their type according to their sides lengths, and find their perimeters. (10 min)

Step 6

Divide the students in 3 groups. The members of the first group are the students who worked with equilateral triangles in Step 2, the second group members are the students with the isosceles triangles, and the third group members - those who worked with scalene triangles. Give each group the page with the corresponding type of triangle (Handout 6). Distribute one A3 size sheet of paper to each group. Students are asked to cut out and use the triangles to create a picture to represent a real-life situation; they can also draw some extra elements and color it. Each group chooses one or two of its members, who present their artistic work to the rest of the class. (20 min)

• 1. Ask the questions:

1. Did you learn something useful today? What is it?
2. Which activity did you like most?

• The energizer Triangle or Circle.
• The relaxing activity Triangle of friendship.
• Step 4: connecting the dots and spotting the same type of triangles.
• Step 6: artistic work.
• 2. Provide a picture of a traffic lights to each student (Handout 7). Ask them to colour the light which indicates how they feel at the end of the lesson.

• green stands for being satisfied with the completed work and having understood everything presented during the lesson;
• yellow stands for not understanding some of the tasks and not particularly liking the lesson;
• red stands for being dissatisfied with the lesson.

(3 min)

Handout 1

Handout 2

Annex 3

Handout 4

Handout 5

Handout 6

Handout 7