76
Review: equations, length and time
Textbook: Part 2, lesson 73, pp. 68–69
GoalUnit review: equations, length, time and self-check.
New words
review · takrorlashquantity (something measurable) · kattalikmass · massaself-check · o‘zini tekshirish
Explanation
This lesson reviews the main topics of Part 2: three-digit numbers, equations, length (m, dm, cm, mm), perimeter and time. A quantity is something we can measure: length, mass (kg), time (hours, minutes). Colour and taste are not quantities. In a test, work out the answer yourself first and then pick it from the choices.
Worked examples
356 + x = 725: x = 725 − 356 = 369.
A triangle with sides 3 cm, 4 cm, 5 cm has perimeter 3 + 4 + 5 = 12 cm.
Class activity
“Mini test”: put five questions on the board (equation, measure, clock, perimeter, comparison). Children show their answer with an A, B or D card and then the class checks together.
Practice
1
Solve: 356 + x = 725. x = ?
369
2
What is 872 − x when x = 46?
826
3
A triangle has sides 3 cm, 4 cm, 5 cm. What is its perimeter in cm?
12
4
One film starts at 11:40 and another at 12:25. How many minutes apart?
45