"Addition and Subtraction of Rational Numbers" PPT courseware

Description

"Addition and Subtraction of Rational Numbers" PPT courseware

learning target:

1. Experience the process of exploring the addition of rational numbers, experience the significance of addition of rational numbers, and understand the rules of addition of rational numbers.

2. Be able to skillfully apply rules to perform addition operations of rational numbers.

3. By using the number axis to explore the process of adding rational numbers, you can further experience the idea of ​​combining numbers and shapes.

Focus: Understand and apply the rules of rational number addition.

Difficulty: Understand the rules for adding rational numbers, especially the rules for adding two numbers with different signs.

Activity 1: (1) The sea water rose by 2 centimeters, and then rose by 3 centimeters. How many centimeters in total did it rise?

(2) The sea water dropped by 2 centimeters, and then dropped by 3 centimeters. How many centimeters did it drop in total?

Observing these two calculations, what is the relationship between the sign of the sum and the sign of the addend? How does the absolute value of the sum relate to the absolute value of the addend?

To summarize the rational number addition rule 1:

Adding two numbers with the same sign takes the same sign,

and add the absolute values.

Activity 2: (3) The sea water rose by 2 centimeters and dropped by 3 centimeters. How many centimeters did it rise in total?

(4) The sea water dropped by 2 centimeters and then rose by 3 centimeters. How many centimeters did it rise in total?

(5) The sea water dropped by 3 centimeters and then rose by 3 centimeters. How many centimeters did it rise in total?

Observing these two calculations, what is the relationship between the sign of the sum and the sign of the addend? How does the absolute value of the sum relate to the absolute value of the addend?

To summarize the rational number addition rule 2:

To add two numbers with different signs, take the sign of the addend with the larger absolute value.

And subtract the smaller absolute value from the larger absolute value.

The addition of two numbers that are opposites of each other gives 0;

Rules for addition of rational numbers:

(1) Add two numbers with the same sign, take the same sign, and add the absolute values.

(2) When adding two numbers with different signs, take the sign of the addend with the larger absolute value and subtract the smaller absolute value from the larger absolute value.

(3) The addition of two numbers that are opposites of each other gives 0.

(4) If you add a number to 0, you still get this number.

Write the result directly:

(1)15 + (-22) =

(2)(-13)+(-8)=

(3) (-0.9) + 1.5 =

(4)2.7 + (-3.5) =

Compete to see who is the cleverest and fastest!

Summary

1. The addition rule of rational numbers;

2. A rational number consists of two parts: sign and absolute value. When adding two rational numbers with the same sign or different signs, first determine the type of addition, then determine the sign of the sum, and finally determine whether the absolute value is a sum or a difference.

Keywords: Teaching courseware for addition and subtraction of rational numbers, Qingdao edition seventh grade mathematics volume PPT courseware download, seventh grade mathematics slide courseware download, addition and subtraction of rational numbers PPT courseware download, .PPT format;

For more information about the PPT courseware "Addition and Subtraction of Rational Numbers", please click the Addition and Subtraction of Rational Numbers ppt tag.

"Addition and Subtraction of Rational Numbers" PPT courseware 2:

"Addition and Subtraction of Rational Numbers" PPT Courseware 2 Knowledge and Skills 1. Be proficient in the addition and subtraction operation rules of rational numbers. 2. Be able to perform mixed operations of addition and subtraction of rational numbers to cultivate students' calculation ability. Process and method - through the calculation of rational numbers Mixed operations of addition and subtraction...

File Info

Update Time: 2024-10-05

This template belongs to Mathematics courseware Qingdao Edition Seventh Grade Mathematics Volume 1 industry PPT template

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