Topicm819649e9a02ff5b6_1528449000663_0Topic

SubtractionsubtractionSubtraction of natural numbers in memory

Levelm819649e9a02ff5b6_1528449084556_0Level

Second

Core curriculumm819649e9a02ff5b6_1528449076687_0Core curriculum

II. Mathematical operations on natural numbers. Student:

1) adds and subtracts natural numbers, two‑digit or higher, adds a single‑digit number to any natural number and subtracts from any natural number.

Timingm819649e9a02ff5b6_1528449068082_0Timing

45 minutes

General objectivem819649e9a02ff5b6_1528449523725_0General objective

Performing uncomplicated calculations in memory or more difficult tasks in writing and the use of these skills in practical situations.

Specific objectivesm819649e9a02ff5b6_1528449552113_0Specific objectives

1. Discovering the subtractionsubtractionsubtraction properties.

2. Using different methods of subtractionsubtractionsubtraction of two‑digit natural numbers in memory.

3. Communicating in English, developing mathematical and basic scientific, technical and IT competences, developing learning skills.

Learning outcomesm819649e9a02ff5b6_1528450430307_0Learning outcomes

The student:

- discovers the subtraction properties,

- uses different methods of subtractionsubtractionsubtraction of two‑digit natural numbers in memory.

Methodsm819649e9a02ff5b6_1528449534267_0Methods

1. Discussion.

2. JIGSAW.

Forms of workm819649e9a02ff5b6_1528449514617_0Forms of work

1. Group work.

2. Individual work.

Lesson stages

Introductionm819649e9a02ff5b6_1528450127855_0Introduction

Students:

Try to remind what subtraction of natural numbers is about, what the numbers that we subtract and the result of subtraction are called.m819649e9a02ff5b6_1527752263647_0Try to remind what subtraction of natural numbers is about, what the numbers that we subtract and the result of subtraction are called.

Individual work:

Students work individually using computers. Their task is to get acquainted with an interactive illustration describing the numbers occurring in the subtractionsubtractionsubtraction.

[Interactive graphics 1]

Procedurem819649e9a02ff5b6_1528446435040_0Procedure

Work in groups.

The teacher divides the class into three groups. Each of them receives a worksheet.

Pupils discuss in groups the issues presented in the worksheets, answer questions, draw conclusions. After completing the task, the student's representative presents the conclusions of the group to the whole class.

GROUP 1 - worksheet
Familiarize yourself with the example below.

[Illustration 1]

Using the example, complete the graphs and notes next to the graphs. Then answer the question:

How can I check if the subtraction was dane correctly?

[Illustration 2]

[Illustration 3]

[Illustration 4]

GROUP 2 - worksheet
Make calculations. Then write the answer to the question: What is the differencedifferencedifference of the numbers if the subtrahend is equal the minuendminuendminuend?

a) 7 - 7,

b) 20 - 20,

c) 15 - 15,

d) 35 – 35.

GROUP 3 - worksheet
In the dotted blank space, enter the appropriate number. Then write the answer to the question: What number is the subtrahendsubtrahendsubtrahend if the minuendminuendminuend is equal the differencedifferencedifference?

a) 7 - ...... = 7,

b) 20 - .... = 20,

c) 15 - ..... = 15,

d) 35 - ..... = 35.

Conclusions student should present to other groups:

- The correctness of the subtractionsubtractionsubtraction can be checked by addingaddingadding.

- If the subtrahendsubtrahendsubtrahend is equal to the minuendminuendminuend, then the differencedifferencedifference is zero.

- If the subtrahendsubtrahendsubtrahend is equal to zero, then the differencedifferencedifference is equal to the minuendminuendminuend.

The JIGSAW method

The teacher divides the students into groups of 3 people. Each student receives a different task to solve.

After solving the task, students meet in groups that have solved the same task. They discuss the solutions and explain the doubts presented by the method.

Then they return to the initial groups and present their solutions and the method used, to other members of the group.

Task
Analyze the following method of subtracting two two‑digit numbers in memory.

[Interactive graphics 2]

Using the method presented in the figure, calculate the given differences:

a) 38 - 25,

b) 87 - 56,

c) 59 - 22,

d) 76 - 65.

Task
Analyze the following method of subtracting two two‑digit numbers in memory.

[Illustration 1]

Using the method presented in the figure, calculate the given differences:

a) 38 - 29,

b) 54 - 36,

c) 73 - 25,

d) 54 - 18.

Task
Analyze the following method of subtracting two two‑digit numbers in memory.

[Illustraion 2]

Using the method presented in the figure, calculate the given differences:

a) 38 - 29,

b) 54 - 36,

c) 73 - 25,

d) 54 - 18.

Students use the acquired skills to solve tasks.

Task
Calculate the differences by any method and check the result by addingaddingadding.

a) 90 - 79,

b) 91 - 56,

c) 46 - 27,

d) 54 - 39,

e) 83 - 36,

f) 63 - 56.

Task
Solve the following word problems, using the subtractionsubtractionsubtraction methods learned in the lesson.

a) There were 35 tulips in the vase, a mother took 19 flowers. How many tulips remained in the vase?

b) Tomek had 50 zloty. He bought a book for 26 zloty. How much change did he receive?

An extra task:
How did the differencedifferencedifference change if the minuendminuendminuend decreased by 11, and the subtrahendsubtrahendsubtrahend increased by 6?

Lesson summarym819649e9a02ff5b6_1528450119332_0Lesson summary

Students do revision exercises.

Then they summarize the lesson together, formulating conclusions to remember:

- The correctness of the subtraction can be checked by adding.

- If the subtrahendsubtrahendsubtrahend is equal to the minuend, then the differencedifferencedifference is zero.

- If the subtrahend is equal to zero, then the differencedifferencedifference is equal to the minuend.

Selected words and expressions used in the lesson plan

addingaddingadding

checking the resultchecking the resultchecking the result

correctness of subtractioncorrectness of subtractioncorrectness of subtraction

differencedifferencedifference

minuendminuendminuend

subtractionsubtractionsubtraction

subtrahendsubtrahendsubtrahend

sum/ totalsum/ totalsum/ total

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subtraction1
subtraction

odejmowanie

R17GfJ6r4Zh351
wymowa w języku angielskim: subtraction
difference1
difference

różnica – wynik odejmowania dwóch liczb

Rc2aCwQNyzWcp1
wymowa w języku angielskim: difference
subtrahend1
subtrahend

odjemnik – liczba, którą odejmujemy

R1LZ57UtYOVzs1
wymowa w języku angielskim: subtrahend
minuend1
minuend

odjemna - liczba od której odejmujemy

R1B1bLH7IQ0fs1
wymowa w języku angielskim: minuend
adding1
adding

dodawanie

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wymowa w języku angielskim: adding
checking the result1
checking the result

sprawdzenie

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wymowa w języku angielskim: checking the result
correctness of subtraction1
correctness of subtraction

poprawność odejmowania

R5br6IFmdd9vS1
wymowa w języku angielskim: correctness of subtraction
sum/ total1
sum/ total

suma

R1JJWP8URx9gD1
wymowa w języku angielskim: sum / total