"Rational Numbers" Rational numbers and their operations PPT

Description

"Rational Numbers" Rational numbers and their operations PPT

Part One Content: Teaching Process:

1. The origin of numbers

An ancient hunter shot an eagle. How to represent an eagle using numbers - with integers.

Two people share a watermelon. How to express half a watermelon using numbers - there is a fraction.

For currency shopping, how to express 2 yuan, 3 jiao and 4 cents using numbers - with decimals.

2. Negative numbers come from life

Example 1. On February 3, the temperature in Shenzhen is 15°C above zero, and the temperature in Harbin is minus 10°C. If it is 15°C above zero, it is expressed as +15°c. How to express minus 10°C?

Example 2: Our country has the world’s highest peak, Mount Everest, which is 8,848 meters higher than the sea level. In Xinjiang, there is also the Turpan Basin, which is 155 meters lower than the sea level. If the height of the sea level is zero degrees, then their How are the heights expressed?

3. The concept of positive and negative numbers

Numbers greater than zero, such as +5, +1.2, +1/2, etc., are called positive numbers. They are all larger than zero.

Numbers such as -5, -1.5, -1/2, etc. with a "-" sign in front of a positive number are called negative numbers, and they are all smaller than zero.

"0" is neither a positive number nor a negative number. "0" has neutral characteristics.

4. Use positive and negative numbers to express quantities with opposite meanings in life.

Discuss: Give some examples in life such as increase and decrease, rise and fall, profit and loss, above and below zero, income and expenditure, etc.

Rational numbers PPT, part 2: analysis of examples

Example 1 (1) In a knowledge contest, if +10 points means adding 10 points, how do you express deducting 20 points?

Solution: (1) Deduct 20 points and record it as -20 points.

(2) When someone turns the turntable, if +5 turns means 5 turns in the counterclockwise direction, how does it mean 12 turns in the clockwise direction?

(2) 12 turns in the clockwise direction are recorded as -12 turns.

(3) In a certain table tennis quality inspection, a table tennis ball exceeding the standard mass by 0.02 grams is recorded as +0.02 grams. So what does -0.03 grams mean?

(3) -0.03g means that the mass of the table tennis ball is 0.03g lower than the standard mass.

Rational numbers PPT, part 3: classroom training

(1) If 5°C above zero is recorded as +5°C, what should minus 3°C be recorded as?

(2) East and west are two opposite directions. If -4 meters means an object moves 4 meters westward, what does +2 meters mean? What do you remember when an object stays put?

(3) A certain warehouse shipped 7.5 tons of flour, so what should be recorded as the shipment of 3.8 tons?

True or False:

1. If -50 yuan means an expenditure of 50 yuan, then +200 yuan means an income of 200 yuan. ( )

2. If +10 means arriving at school 10 minutes early, then -5 means arriving at school 5 minutes late. ( )

Rational numbers PPT, part 4 content: Summary:

This lesson introduces the concepts of negative numbers and rational numbers through examples, learns how to express negative numbers, and correctly categorizes rational numbers.

Homework:

Knowledge and skills: 2, 3, 4, 5;

Mathematical understanding and problem solving.

Keywords: Beijing Normal University edition seventh-grade mathematics PPT courseware free download, rational numbers PPT download, rational numbers and their operations PPT download, .PPT format;

For more information about the "Rational Numbers and Their Operations Rational Numbers" PPT courseware, please click the Rational Numbers and Their Operations PPT Rational Numbers PPT tag.

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Update Time: 2024-11-21

This template belongs to Mathematics courseware Beijing Normal University Edition Seventh Grade Mathematics Volume 1 industry PPT template

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