Topicmfbd1c144215ab41d_1528449000663_0Topic

Tasks with a calculatorcalculatorcalculator

Levelmfbd1c144215ab41d_1528449084556_0Level

Second

Core curriculummfbd1c144215ab41d_1528449076687_0Core curriculum

II. OperationsoperationsOperations on natural numbers. The student:

2) adds and subtracts multi digit natural number using the written method or a calculatorcalculatorcalculator;

3) multiplies and divides a natural number by a one digit, two digit and three digit natural number in his head (the simplest examples) and using a calculator (in more difficult examples).

Timingmfbd1c144215ab41d_1528449068082_0Timing

45 minutes

General objectivemfbd1c144215ab41d_1528449523725_0General objective

Performing simple operations in the student’s head or more complicated operationsoperationsoperations using the written methods well as applying these skills in practical situations.

Specific objectivesmfbd1c144215ab41d_1528449552113_0Specific objectives

1. Communication in English, developing mathematical, IT and basic scientific and technical competence, developing learning skills.

2. Getting to know the structure and the functioning of a calculatorcalculatorcalculator.

3. Performing operationsoperationsoperations with the use of a calculator.

Learning outcomesmfbd1c144215ab41d_1528450430307_0Learning outcomes

The student:

- gets to know the structure and computational capabilities of a calculator,

- calculates the value of arithmetic expressions with the use of a calculatorcalculatorcalculator.

Methodsmfbd1c144215ab41d_1528449534267_0Methods

1. The number spider.

2. The swing.

Forms of workmfbd1c144215ab41d_1528449514617_0Forms of work

1. Individual work.

2. Group work.

Lesson stages

Introductionmfbd1c144215ab41d_1528450127855_0Introduction

Using the method of a „number spider” the students recollect methods of performing operations on natural number and properties of these operationsoperationsoperations. The game is started by a volunteer “a spider”. This person gives two large natural numbers, which should be added using the written method. This person stands in the middle of the class and nominates one of the students. If the student performs the operation correctly on the blackboard, he stands next to the “spider” as the second element of the web (the circle formed by the students). If the operationsoperationsoperations isn’t performed correctly , the student is caught in the web ( he will stay inside the circle). The student who does the calculationscalculationscalculations correctly gives two numbers, which need to be e.g. multiplied. Then, he nominated another student and so the game goes on. The instructions should involve both performing operations and giving the properties.

Discussion – is it always easy to perform operationsoperationsoperations on large numbers? Why doesn’t a cashier make calculationscalculationscalculations in her head? In what situations is it unacceptable to miscalculate?

The summary of this discussion could be the following conclusion:
If we need to calculate something fast, a calculator can be really helpful. It doesn’t have to be a separate device, as a calculator app is often installed in mobile phones and computers.mfbd1c144215ab41d_1527752263647_0If we need to calculate something fast, a calculator can be really helpful. It doesn’t have to be a separate device, as a calculator app is often installed in mobile phones and computers.

Proceduremfbd1c144215ab41d_1528446435040_0Procedure

The teacher informs the students that the aim of the class is getting to know the method of calculating with the use of a calculatorcalculatorcalculator. Then, the teacher discusses the structure of a calculator, paying special attention to all the buttons and their function. The teacher gives some examples of calculationscalculationscalculations, which the students make on their calculators.

Task
Calculate using your calculator:

a) 124567 + 345689,

b)54321 – 12345,

c) 9876 ∙ 789,

d) 675480 : 40.

Task
Calculate using your calculatorcalculatorcalculator:

a) 125 ∙ 25 + 120550 : 25,

b) 532 : 2 - 345 : 5,

c) 235Indeks górny 2² – 23Indeks górny 2²,

d) 11Indeks górny 3³ : 11Indeks górny 2² ∙ 1087.

Task
Calculate. Observe the results you got. Add next lines without any calculationscalculationscalculations. Check if your suggestions were correct:

a)
8888 + 33 + 9 + 0
8888 + 33 + 9 + 1
8888 + 33 + 9 + 2
8888 + 33 + 9 + 3
..........................
..........................
..........................

b)
9 + 8 + 6 + 6666
8 + 8 + 6 + 6666
7 + 8 + 6 + 6666
6 + 8 + 6 + 6666
..........................
..........................
..........................

Working in groups with the “swing” technique. Each group writes 4 examples of multiple operation arithmetic expressions and passes them to another group. This group calculates the expressions using their calculators and writes down the calculationscalculationscalculations. In the “swing” technique two examples should be calculated correctly (the swing is up) and two incorrectly (the swing is down). The piece of paper goes to another group whose task is to find and correct the mistakes.

While discussing the results of their work, the students consider how to find miscalculations most easily.

Task
The students work individually using their computers. Their task is to solve the problem presented in the applet. Next, they should perform the same calculationscalculationscalculations with their calculators and draw conclusions.

[Geogebra applet]

The conclusion that should be drawn by the students:
Making calculations on a calculator we often get approximate values of given arithmetic expressions.mfbd1c144215ab41d_1527752256679_0Making calculations on a calculator we often get approximate values of given arithmetic expressions.

The students use their skills to solve the tasks.

Task
Calculate on a calculatorcalculatorcalculator. Decide if the resultresultresult is precise or approximate:

a) 560098 + 1245,

b) (7568 – 234) : 5,

c) (9876 + 1234) : 100 + 967 ∙ 15,

d) 999777 - 2222 : 11 + 145 ∙ (1800 - 800).

An extra task
Replace the dots which numbers so as to get the precise resultresultresult:

(665544 - 333222) : …… + 12325 : (589 - ……).

The teacher summarizes the students’ work, explains the doubts and gives marks to the most active students.

Lesson summarymfbd1c144215ab41d_1528450119332_0Lesson summary

The students do the consolidation tasks.

Then, they summarize the class and formulate conclusions to memorize:

- If we need to make the calculations fast, a calculator can be really helpful.
- Making calculations on a calculator we often get approximate values of given arithmetic expressions.mfbd1c144215ab41d_1527712094602_0- If we need to make the calculations fast, a calculator can be really helpful.
- Making calculations on a calculator we often get approximate values of given arithmetic expressions.

Selected words and expressions used in the lesson plan

approximate valueapproximate valueapproximate value

arithmetic expressionarithmetic expressionarithmetic expression

calculationscalculationscalculations

calculatorcalculatorcalculator

operationsoperationsoperations

precise valueprecise valueprecise value

resultresultresult