☰ Contents · Mathematics

Equal shapes, tangram, symmetry and solid shapes

Lessons 124–128 · 5 lessons · I.V. Repyova, Y.V. Zemlina. Mathematics Grade 1, Parts 1–4. Novda Edutainment, 2023
124

Equal (congruent) shapes

Textbook Part 4, pp. 28–29
GoalKnow that shapes which match exactly when laid on top of each other are equal.
New words
equal (congruent) shapes · teng shakllarone on top of the other · ustma-ustto match · mos kelmoq
Explanation

If two shapes laid on top of each other match at every side and corner, the shapes are equal. Equal shapes also have equal perimeters. But shapes with equal perimeters are not always equal!

Worked examples
Two squares with 3 cm sides are equal shapes.
A 4 by 4 square and a 6 by 2 rectangle: both have perimeter 16 cm, but they are not equal shapes.
Class activity

Children cut shapes from paper, lay them on top of each other to find equal pairs, and colour each pair the same.

Practice
1
Do equal shapes have equal perimeters?
2
A 5 by 5 square and a 7 by 3 rectangle. Their perimeters?
3
Bobur and Ahmad did not make the red fish. Bobur and Alisher did not make the yellow fish. Who made the green fish?
4
40 + 14 = ?