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Multiplication and division the decimal numbers by 10, 100, 1000, ...
SCENARIO OF THE LESSON
Aims of lesson:
The aim of lesson is to notice, formulate and use the activities the principle of multiplaying and division decimal numbers through 10, 100, 1000, .... Moreover the students practise the skills of doing exercises on decimal numbers with the usage of a calculator, reading decimal numbers and counting in memory. Teaching methods:
Counting with a calculator - noticing a "wandering" comma,
Speaking - formulation of relevant conclusion,
Exercises - usage of the newly learnt principles in exercises. Organizational forms:
Whole class work, pair work Didactic means:
Calculators (one per two persons), sheets of paper with exercises
The structure of the lesson: - Introduction (about 10 min)
- Organizational activities
- Preparing for a new lesson
- The main part (about 30 min)
- Couting the rules (division by 10, 100, 1000, ...) with a calculator
- Noticing "wandering" comma
- Formulation and writting down a conclusion
- Practising newly learnt principle
- Couting the rules (multiplication by 10, 100, 1000, ...) with a calculator
- Noticing "wandering" comma
- Formulation and writting down a conclusion
- Practising newly learnt principle
- Exercises in multiplying and dividing decimal numbers by 10, 100, 1000
- Final part (about 15 min)
- Summery of lesson
- Explaining homework
Main parts of the lesson
Teacher's activities | Possible student's activities |
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1. Teacher distributes the paper with exercises.
Count the rules with calculator and write the appropriate outcomes. Work in pairs.
| Students are given the sheets of paper:
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12 345:10=............................
12 345:100=..........................
1 2 345:1000=.......................
12 345:10 000=.....................
12 345:100 000=...................
12 345:1 000 000=................
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and write the outcomes:
1234,5
123,45
..........
0,12345
0,012345 | | 1. a) What can you notice? | The comma is moving | | Does the comma move according to some principle? | Yes | How many positions the comma has moved when we divide by 10?
In which direction? | One place left. | | How the position of comma has changed when we divide by 1000? | The comma moved tree places left | 1. b) Teacher ask the students to stick the sheets of paper to notebooks and together with students formulates the principle.
| Students stick the sheets of paper to notebooks and write in colour:
When dividing the decimal numbers by 10, 100, 1000, ... we move the comma about one, two, three places left. | 2. The teacher writes on the board the rule:
6723,5:_______=67,235
N: What number the divisor is? | The divisor is 100 | N: Why 100?
| Because the comma was moved two places left. | The teacher writes on board the rules:
49568:________=49,568
69,978:________=0,0069978 | Some of the students complete the blanks.
| | 3. Have you ever heard about pi number? | U: Yes/No | | N: It is some mathematical constant with which you will meet in counting the field of a circle. Its value is equal 3,14159265... | | 3. Teacher distributes the paper with exercises.
Count the rules with calculator and write the appropriate outcomes. Work in pairs.
| Students are given the sheets of paper:
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3,14159265*10=.........................
3,14159265*100=.......................
3,14159265*1000=.....................
3,14159265*10 000=..................
3,14159265*100 000=................
3,14159265*1 000 000=.............
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and write the outcomes:
31,4159265
314,159265
.......
314159,265
3141592,65 | | 3. a) What can you notice? | The comma is movng, but this time to the right. | How many positions the comma moved when we multiply by 10?
And when we multiply by 1000? | One place
Three places | 3. b) Teacher ask the students to stick the sheets of paper to notebooks and together with students formulates the principle.
| Students stick the sheets of paper to notebooks and write in colour:
When multiplying the decimal numbers by 10, 100, 1000, ... we move the comma about one, two, three places right. | 4. The teacher writes on the board the rule:
37,56*________=375,6
What number the factor is? | The factor is 10 | Why 10?
| Because the comma was moved one place right. | The teacher writes on board the rules:
0,03756*________=375,6
375,6*________=375600 | Some of the students complete the blanks.
| What differences can you see beetwen the principles of dividing and multiplying the decimal numbers by 10, 100, 1000, ...?
| While dividing the comma moved left,
while multiplying the comma moved right. | 5. The teacher writes on the board the rules:
a) 1,75 _ _____=17,5
b) 14,3 _ _____=1,43
c) 98,547 _ _____=9854,7
d) 987,47 _ _____=9,8747
e) 67,32 _ _____=67320
f) 845,6 _ _____=0,8456
Write and complete the blanks with appropriate signs and numbers. | Students write the rules and doing exercises.
Some of students read the outcomes
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Homework Translations: Polish German
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