Around the Earth. This choice of units is due to both historical and practical considerations: the need to coordinate the activities of people with the change of day and night or seasons.

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✪ The concept of time as a quantity. Day is a unit of time. Hour.

✪ “Time. Units of measurement of time "- Gordikova E.A.

✪ Time units year, month, day,

✪ Units of time. Second. Time unit - century | Mathematics Grade 4 # 23 | Info lesson

✪ What is time?

Subtitles

Day, hour, minute and second

Historically, the main unit for measuring short time intervals has been a day (often referred to as "day"), measured by the minimum complete cycles of solar illumination change (day and night).

As a result of dividing the day into smaller time intervals of the same length, hours, minutes and seconds arose. The origin of division is probably associated with the duodecimal number system, which was adhered to in ancient Sumer. The day was divided into two equal consecutive intervals (conventionally day and night). Each of them was divided by 12 hours ... Further division of the hour goes back to the sexagesimal number system. Every hour was divided by 60 minutes ... Every minute - by 60 seconds .

Thus, there are 3600 seconds in an hour; in a day - 24 hours, or 1440 minutes, or 86,400 seconds.

Hours, minutes and seconds have become part of our everyday life, they have become naturally perceived even against the background of the decimal number system. Now it is these units that are most often used to measure and express periods of time. Second (Russian designation: with; international: s) is one of the seven basic units in the International System of Units (SI) and one of the three basic units in the CGS system.

Units "minute" (Russian designation: min; international: min), "Hour" (Russian designation: h; international: h) and "day" (Russian designation: days; international: d) are not included in the SI system, but in the Russian Federation they are approved for use as off-system units without limiting the validity period of the admission with the scope of "all areas". In accordance with the requirements of the Brochure SI and GOST 8.417-2002, the name and designation of the time units "minute", "hour" and "day" are not allowed to be used with sub-multiples and multiple SI prefixes.

Astronomy uses the notation h, m, with (or h, m, s) in the superscript: for example, 13 h 20 m 10 s (or 13 h 20 m 10 s).

Use to indicate time of day

First of all, hours, minutes and seconds were introduced to facilitate the indication of time coordinates within a day.

A point on the time axis within a specific calendar day is indicated by an indication of the whole number of hours that have passed since the beginning of the day; then a whole number of minutes that have passed since the beginning of the current hour; then an integer number of seconds that have passed since the beginning of the current minute; if it is necessary to specify the time position even more precisely, then the decimal system is used, indicating the past fraction of the current second (usually to hundredths or to thousandths).

Letter designations "h", "min", "s" are usually not written on a letter, but only numbers separated by a colon or a period are indicated. Minute and second number can range from 0 to 59 inclusive. If high precision is not required, the number of seconds is not indicated.

There are two systems for indicating the time of day. In the so-called French system, the division of the day into two intervals of 12 hours (day and night) is not taken into account, but it is believed that the day is directly divided into 24 hours. The hour number can be from 0 to 23 inclusive. In the "English system" this division is taken into account. The hours indicate from the beginning of the current half-day, and after the numbers they write the alphabetic index of the half-day. The first half of the day (night, morning) is designated AM, the second (day, evening) - PM; these designations come from lat. ante meridiem and post meridiem (before noon / afternoon). The number of the hour in 12-hour systems in different traditions is written in different ways: from 0 to 11 or 12, 1, 2,…, 11. Since all three temporary subcoordinates do not exceed one hundred, two digits are sufficient to write them in the decimal system; therefore, the values \u200b\u200bof hours, minutes and seconds are written in two-digit decimal numbers, adding a zero in front of the number, if necessary (in the English system, however, the hour number is written in one- or two-digit decimal numbers).

Midnight is taken as the beginning of the countdown. Thus, midnight is 00:00 in French and 12:00 AM in English. Noon - 12:00 (12:00 PM). [ ] The time after 19 hours and another 14 minutes from midnight is 19:14 (in English - 7:14 PM).

On the dials of most modern watches (with hands), it is the English system that is used. However, such analogue watches are also produced where the French 24-hour system is used. Such clocks are used in those areas where it is difficult to judge the day and night (for example, on submarines or beyond the Arctic Circle, where there is a polar night and a polar day).

Use to indicate a time interval

For measuring time intervals, hours, minutes and seconds are not very convenient, since they do not use the decimal number system. Therefore, only seconds are usually used to measure time intervals.

However, sometimes the actual hours, minutes and seconds are used. So, the duration of 50,000 s can be written as 13 h 53 min 20 s.

Standardization

Based on the SI second, the minute is defined as 60 seconds, the hour as 60 minutes, and the calendar (Julian) day as exactly 86,400 s. The Julian day is currently shorter than the average solar day by about 2 milliseconds; to eliminate the accumulating discrepancies, leap seconds are introduced. The Julian year is also defined (exactly 365.25 Julian days, or 31,557,600 s), sometimes called the scientific year.

In astronomy and in a number of other fields, along with the SI second, the ephemeris second is used, the definition of which is based on astronomical observations. Assuming that there are 365.24219878125 days in a tropical year, and assuming a constant duration (the so-called ephemeris calculus), we get that 31,556,925.9747 seconds in a year. Then it is believed that a second is 1 ⁄ 31 556 925,9747 part of the tropical year. The secular change in the duration of the tropical year forces us to tie this definition to a certain era; thus, this definition refers to the tropical year at the time 1900.0.

Multiples and sub-multiples

The second is the only time unit with which SI prefixes are used to form sub-multiples and (rarely) multiples.

Year, month, week

For longer time intervals, the units of measure are year, month and week, consisting of an integer number of solar days. The year is approximately equal to the period of the Earth's revolution around the Sun (approximately 365.25 days), the month is the period of the complete change of the phases of the moon (called the synodic month, equal to 29.53 days).

In the most common Gregorian, as well as in the Julian calendar, a year equal to 365 days is taken as a basis. Since the tropical year is not equal to the whole number of solar days (it is approximately 365.2422 days), leap years of 366 days are used to synchronize the calendar seasons with the astronomical ones in the calendar. The year is divided into twelve calendar months of varying duration (from 28 to 31 days). Usually, there is one full moon for each calendar month, but since the phases of the moon change slightly faster than 12 times a year, sometimes there are also the second full moons of the month, called the blue moon.

Century, millennium

Even larger units of time are a century (100 years) and a millennium (1000 years). A century is sometimes divided into decades (decades).

Megagod and gigagod

In foreign language literature, such multiple units of time as megaod (notation Myr) equal to a million years, and gigagod (notation Gyr) equal to a billion years. These units are used mainly in cosmology, as well as in geology and in the sciences related to the study of the history of the Earth. So, for example, the age of the universe is estimated at 13.72 ± 0.12 gigalets. In Russian-language literature, such units are rarely used, their use also contradicts the "Regulations on the units of quantities allowed for use in the Russian Federation", according to which the unit of time year (just like, for example, a week, month, century, millennium) should not be used with multiples and sub-multiples.

Rare and obsolete units

In the UK and the Commonwealth of Nations, the unit of measurement for fortnight is two weeks.

If you want to know the topic of the lesson, guess the riddle: "What's going on without moving?" Of course, this is the time. In this lesson, students are given the opportunity to learn some units of time measurement: year, month, day, get acquainted with methods of determining time from the ancient Egyptians to the present day, and also practice translating one time unit into others, in solving problems with ingenuity.

WHAT IS TIME?

This question was probably asked by every person. In the modern world, it is very important to know what time is. Departures of trains, aircraft departures, the start of the working day, classes in schools, sports events and television broadcasts - all this happens at exactly the appointed time.

Why do you think they sometimes say "lost time"? Is it possible to waste time, for example, like a pencil or a book?

In many European languages, "time" is one of the most common nouns.

In Russian, we can also find many expressions with this word. You've probably heard them.

• No time.
• Time flies.
• Time is like rubber.
• Spend time.
• Kill time!
• Plenty of time!
• To save time.

Then let's not waste time and get to work.

It is about time, the units of time that we learn today.

Observations of the Sun, Moon and stars helped people measure time. Already ancient people noticed the alternation of day and night, the change of seasons. The first units of time appeared: day and year.

The length of the year was initially determined very imprecisely.

For example, the ancient Egyptians considered the period of time from one flood of the Nile to another as a year.

Then they noticed that the flooding of the Nile was associated with the appearance of the bright star Sirius above the horizon. The year has become more precise. The Egyptians invented one of the most successful calendars. They divided the year into 12 months of 30 days. This calendar served as a model for other peoples.

Year - a period of time approximately equal to the period of the Earth's revolution around the Sun.

In astronomy, there are star, solar, lunar, calendar years.

The year contains 365 days, but every fourth year is a leap year. It contains 366 days.

The year can be divided into 4 time intervals (4 seasons) or you can also divide the year into 12 months.

Month - a time interval close to the period of the Moon's revolution around the Earth.

The time from one full moon to the next is 29 and a half days.

Day - a period of time approximately equal to the period of the Earth's revolution around its axis.

A day is a unit of time equal to 24 hours.

These units of time are cosmic (natural).

There are 12 months in a year.

There are 30 or 31 days in a month.

February 28 or 29 days.

There are 24 hours a day.

Complete the task.

Next to these words, write the word "day" as you think it should be pronounced.

Some ...

Two ...

Five …

Thirty …

Check yourself.

One day

Two days

Five days

Thirty days

Name five days in a row without using the names of the numbers of the month and without naming the days of the week.

Check yourself.

The day before yesterday, yesterday, today, tomorrow, the day after tomorrow.

Compare time units and put comparison signs.

65 days ... 2 months

2 years ... 24 months

3 months … 60 days.

1 year ... 366 days

You can reason like this.

65 days … .2 months

Each month (except February) can have 30 or 31 days. This means that the two longest months last 62 days. And this is less than 65 days.

2 years ... 24 months

We know that there are 12 months in a year, which means that in two years there are 24 months.

3 months … 60 days.

We already recalled that in each month (except February) there can be 30 or 31 days. This means that the three shortest months contain more than 60 days.

1 year ... 366 days

It is unlikely that we will be able to put a comparison sign between these values, since we do not know which year this is - a leap year, which contains 366 days, or not a leap year, in which there are 365 days.

Check yourself.

65 days \u003e 2 months

2 years \u003d 24 months

3 months \u003e 60 days

1 year? 366 days

The train travels to the sea for 2 days, and goes back 48 hours. Why such difference?

Check yourself.

In fact, there is no difference, since two days are 48 hours.

List of references

1. M.I. Moreau, M.A. Bantova and others. Mathematics: Textbook. Grade 3: in 2 parts, part 1. - M .: "Education", 2012.
2. M.I. Moreau, M.A. Bantova and others. Mathematics: Textbook. Grade 3: in 2 parts, part 2. - M .: "Education", 2012.
3. M.I. Moreau. Mathematics Lessons: Guidelines for Teachers. Grade 3. - M .: Education, 2012.
4. Normative legal document. Monitoring and evaluation of learning outcomes. - M .: "Education", 2011.
5. "School of Russia": Programs for primary school. - M .: "Education", 2011.
6. S.I. Volkova. Mathematics: Verification work. Grade 3. - M .: Education, 2012.
7. V.N. Rudnitskaya. Tests. - M .: "Exam", 2012.

1. Nsportal.ru ().
2. Prosv.ru ().
3. Do.gendocs.ru ().

Homework

1. Fill in the missing information.

In a year ... or ... days

In the year… month.

In a month ... or ... days

In February ... or ... days

In a day ... hours

2. Compare.

65 days …. 1 month

4 years ... 48 months

4 months … 60 days.

1 day ... 28 hours.

3. Make an assignment on the topic of the lesson for your peers.

MOU "Yalchik secondary school" of the Yalchik region of the Chuvash republic "

Compiled by the primary teacher

classes MOU "Yalchik secondary school"

with. Yalchiki - 2009

Objectives: To consolidate and generalize the knowledge of children about the previously studied units of time.

Tasks:

Improve computing skills. Teach children to compare units of time with each other. To acquaint students with watches, historical information about the origin of watches. To develop attention, the ability to listen, memorize, thinking, imagination, interest in the subject. To foster the ability to work in a team, independence and discipline.

Complex methodological support of the lesson:

Software : on the teacher's desk a computer, a multimedia projector, a screen, a tape recorder, a disk.

Means of education : Models of clocks, drawings of flowers, cards “Generalization of units of time”, hourglass, cards of units of time.

Teaching methods:

problematic (questions);

mutual control and self-control;

reproductive (repetition and reproduction)

During the classes

І. Organizing time.

The bell rang and fell,
The lesson begins.

II. Knowledge update.

Guys, look at the board. Let's play the Connect Correctly game. You should find pairs of these values. (Children work at the blackboard)

Well done! Now tell me, what can we say about them? What do these quantities have in common? (These are units of time)

What we will talk about in this lesson ? (About units of time)

Guys, today in the lesson we will repeat and generalize the knowledge about the measures of time that we got acquainted with in the lessons of mathematics. We have set goals: to get to know the watch, learn about its origin, and also develop attention, listening skills, memory, thinking ... (Slide 1)

II I. Repetition of what has been learned.

First, let's remember all units of time. Let's play the game "Ladder ". You must arrange the units in ascending order. (Work in notebooks) (Slide 2)

I V ... Information about the clock.

Guys, tell me, where do we use time units?

And to find out what we are going to talk about next, you have to guess the riddle. Listen carefully.

Chĕlkhesur, khalkhasar, văkhat pĕlet. (Sekhet) (Slide 3)

- What is a watch? What are they needed for?

“Now we begin the story about the clock,
About those that were invented before us.
Once electronic clocks were not known.
We got up in the sun, we dined in the sun.
We have never known a capricious clock in nature,
But all the same lateness was not in vogue. " (Slide 4)

Guys, of course, every house has a clock. And, most likely, there are several of them. An alarm clock that helps not to oversleep school, a wall clock with a pendulum and a strike, a convenient electronic and wristwatch. An hourglass can also be seen in the kitchen. But in ancient times there were no such clocks. What was the very first watch?

1 solar clock (Slide 5)

The first hours were sunny. People have long noticed that the longest shadows from objects illuminated by the sun are in the morning, by noon they shorten, and by the evening they lengthen again. They also noticed that shadows change not only in size but also in direction during the day. This phenomenon was used to create the simplest sundial - GNOMON.
The dial of such a watch is a flat horizontal platform, on which a pole (rod, stick, plate) is vertically mounted, casting a shadow. In the morning the shadow of the gnomon is turned to the west, at noon - to the north, and in the evening - to the east.
The dial was marked with 12 divisions. When the shadow of the gnomon passed from one division to another, 1 hour passed.
In ancient times, sundials were widespread. But even today the sundial can be seen in St. Petersburg. The Museum of the Arctic and Antarctica contains three sundials discovered during excavations in Siberia. The sundial has been preserved on Moskovsky Prospekt and on Vasilievsky Island in St. Petersburg, as well as in the city of Pushkin at the Oryol Gate.

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Sundial drawing

Other clocks are directly connected to the sun - they are called floral. The great Swedish botanist Karl Linnaeus noticed that flowers bloom at certain times of the day. He invented the first flower clock.
Observing flowering plants, the scientist determined at what time the corolla of a particular flower opens. Then he planted flowers around the flower bed, which opened one after another, each in its own time.
The dial of such watches is divided into 12 parts in the same way as the dial of ordinary watches. Only in place of the usual numbers is a living floral carpet. Flowers open and close at specific times. Now let's define at what time some flowers open and close. To do this, you need to solve the example and write only the result of calculations in a column in a notebook.

24: 4 \u003d 2x8 \u003d 56: 8 \u003d 5x3 \u003d 64: 8 \u003d 4x4 + 1 \u003d 45: 5 \u003d 3x6 \u003d 70: 7 \u003d 4x5 \u003d

Now let's check. What results did you get on the top line? This is the time when the mac opens and closes (similarly check other lines ). (Slide 6)

6-16 Poppy 7-15 Dandelion 8-17 Violet 9-18 Mother-and-stepmother 10-20 Water lily

Now we will solve problems. You need to write down the solution to the problem in notebooks and show it to me. “The poppy opens at 6:00 and closes at 16:00. How long does it make us happy with its beauty? ”. (16–6 \u003d 10 hours)

“Dandelion opens at 7 o'clock, and Mother and Stepmother at 10 o'clock. How much earlier does a dandelion unfold than a mother-and-stepmother? " (10-7 \u003d 3)

2.Water clock ( Slide 7)

But the sun does not always shine brightly. And then they came up with the idea of \u200b\u200bmeasuring time with a water clock.

The years passed.

The clock appeared different.

The water clock was called Klepsidroy.

KLEPSYDRA ", which means" water thief ".
A water clock is a vessel from which water constantly flows out through a hole. The hole is so large that all the water flows through it in exactly one hour. Then you need to refill the vessel with water. Then water clocks of the most varied designs were created, and the time was determined by such clocks according to the speed of water flowing from one vessel to another. The vessels had marks that were used to count the time intervals. Slowly flowing out, the water indicated the next mark. So one after another the hours passed - time passed.
Nowadays, the University of Texas in the United States of America has created a hand-held "water" watch with high accuracy.

3 fire clock (Slide 8)

The fire clock was invented in the ancient world.

Sly alarm clock was invented in China.
The thin thread burns out evenly,
The ball is falling, and thundering, and ringing ..
Sonya feared the clock like fire.

One of the fire clocks used by the miners was an earthen vessel with enough oil to burn the lamp for 10 hours. When the oil ran out and the lamp went out, the miner finished his work in the mine.
In China, for a fire clock, dough was prepared from special varieties of wood, ground into powder, from which sticks of various shapes or long spirals were made. Such sticks or spirals could burn for months without requiring maintenance personnel.
A fiery clock is known - an alarm clock. In this watch, metal balls were suspended from a spiral or a stick in certain places, which, when the spiral (sticks) burned, fell into a porcelain vase, making a loud ringing.
A fire clock in the form of a candle with marks on it was widely used. The combustion of a piece of the candle between the marks corresponded to a certain period of time.

ship flasks ".
The hourglass is now widely used in medicine.

It will take one minute to pour sand from one part to another. You need to rewrite the expressions in one minute and compare them, that is, put the signs\u003e,<, =.

Зч * 2h 13min. 1 year * 10 months ... (Slide 10)

1 week * 5 days 1h * 1 day

5. Mechanical watch. (Slide 11)

We do not know exactly when the mechanical watch came into existence. Some believe that it is still in Ancient Greece. In the 14th century, pocket watches appeared. The first mentions of mechanical watches date back to the end of the 6th century. The modern mechanical watch was created in 1657 by the Dutch scientist H. Huygens. Nowadays there are pocket watches and mechanical watches.

Discoveries were born, arguing over time,

The pendulum made a clock for a clock.

“Tick-tock, Tick-tock,” the clock is knocking,
And the mustache swirls under him.
And from above there is a small bell.
The clock is ringing: "Get up, buddy!"
They rush to school, to class.

There are also electronic clocks . This is a modern watch. They don't have arrows. Time is shown by luminous numbers. They change every second, just have time to look. They work from electric current, from batteries. (Slide 12)

Guys, what kind of hours we talked about today. What are they all for?

Vi. Solving problems.

The teacher and the students' desks have the "Clock" equipment.

The clock is used to measure time. Consider a watch face. It has 12 large divisions marked with numbers from 1 to 12. There are 5 small divisions between two adjacent large divisions.

How many small divisions are the dial divided into? (5x12 \u003d 60)

Guys, put the hour hand on division 8 and the minute on division 12. The clock shows 8 o'clock exactly.

Now let's play in game "Show the time". (Slide 13)

- Game "Show the time when you ..." (Slide 14)

Vii. Checking the assimilation of new material

1) The game "Think, decide, show" (Slide 15)

(“Clock” equipment is used)

2) Recover Records game ( select numerical designations for time units)

1 year - 12 months ( Slide16) 1 year - days 1 month - 30 (days 1 week - 7 days 1 hour - 60 minutes

- Guys, all the above-mentioned watches, guys, can be described as lifeless. Are there "live" clocks?

There is a clock in the village
They are not dead, alive,
They walk without a factory
Themselves are avian. (Cock). (Slide 17)

Hearing in the night through a dream the lingering cries of roosters, people tired of the day's work fall asleep with the joyful thought that the night is still ahead. After all, roosters crow like that only at night - drawn out and occasionally. This, as they said in ancient times, is only the “first cry” of a rooster. But now the roosters start to crow more and more, faster and faster. This is the “second cry”. So dawn is coming soon. And the day begins again. Roosters are the best watches, trouble-free

3) The game "Decipher proverbs and sayings." Translation of named numbers. (Slide 18)

Decipher proverbs and sayings by replacing the numbers highlighted in red with larger units of time. Write down all the translations of the named numbers in your notebooks

100 years live, 100 years learn. (Century live, century learn.)

The promised 36 months are waiting. (Promised three years are waiting.)

Business time, but fun 60 minutes. (Business for time, but for fun hour.)

7 days 12 months feeds. (Week of the year feeds.)

What do the proverbs mean by meaning? Which ones will be useful for all students?

VШ. Reflection . Self-examination of work .. (Slide 19)

- Guys, our lesson has come to an end. What did you learn new in the lesson.

Answer me a few questions.

What watch did you already know about? What did you hear about today for the first time?

What was the first watch? (Solar.)

What types of clocks are there? (Water, sand, mechanical, electronic.)

What time units do you know? (Second, minute, hour, day, week, month, year, century, millennium.)

IX. Outcome

Well done! You really did a very good job today and deserves only good marks. And I also want to wish: take care of your time and someone else's.

Class: 4

Objectives:

1. To acquaint children with the new unit of time, to systematize students' knowledge of units of time, to improve computational skills and the ability to solve problems;

2. To develop the ability to transform large units into small ones and vice versa, develop memory, logical thinking;

3. To foster interest in mathematics, accuracy in the design of work, independence, foster the ability to work in a team.

Equipment:textbook MI Moro "Mathematics grade 4", multimedia installation, cards for working in pairs, clock model.

During the classes

I. Organizational moment (slide 1, Appendix 1)

II. Setting the goal and objectives of the lesson. Motivation for learning activities

- Today we will continue to work on the units of time, we will get acquainted with the new unit of time. We will learn to convert time units and improve our computational skills. And most importantly, we will learn to think. Training is essential here, so sit comfortably and close your eyes. Repeat after me: I am at school in my lesson. Now I will begin to study. I am happy about it. My memory is strong. I am ready to work. I am working !!! III. Verbal countingTask 1. Find an extra unit of measurement (slide 2). Arrange the units of measurement in ascending order. Task 2. Find the extra unit of measurement (slide 3). Arrange the units of measure in descending order. Task 3. Working in pairs... Let's recall the units of time measurement. Let's conduct a study on how these units of time are interconnected. You have the opportunity to show how attentive and friendly you are. You have the cards with the task on your tables. Re-establish the correct sequence: 1 minute \u003d 1 hour \u003d 1 day \u003d 1 week \u003d 1 month \u003d 1 year \u003d Check (slide 4). Task 5 (slide 5). Show the time on your watch when you ... "Animation-mathematical minute" (slide 6) Task 1. (slide 6) Problem about Dunno. Dunno wrote poetry about his friends for 5 minutes 17 seconds. How many seconds did he do this difficult job? Task 2. (Slide 7-8) Problem about Winnie the Pooh. Winnie the Pooh was invited to visit the Donkey at 4 o'clock in the afternoon. He left the house at 3 o'clock, taking with him a pot of honey. 15 minutes he got to Piglet's house, 1/6 hour devoured a delicious lunch, 10 minutes examined the empty pot, another 15 minutes consulted with the wise Owl, and 10 minutes wandered with friends to the donkey's dwelling. Were the heroes late for the festive dinner? Physical education for the eyes (slide 9) Follow the ladybug with your eyes without turning your head. III. Working on a new topic- Let's repeat once again in ascending order the units of time known to you. (Slide 10) - There is another large unit of time, popularly called “ century". - How many years do you think it unites? (100 years) - What else is it called? (Century). - What is the 1st century? (100 years old). (Slide 11) - Let's write down the full date (day, month, year, century) in a notebook. - How old is the 21st century? (2100 years old). (Slide 12) - Let's write down: 21st century \u003d 2100 years. Look, there are hundreds missing from this year's (2010) record. Maybe we messed something up? Let's try to figure it out with the number ray. (Slide 13) - Many centuries ago, people agreed on a conditional reference point for time. Let's designate it as 0. (Its presence does not mean that nothing happened until this moment). We talked about the years of our era and the years before our era. So, let's show on the number ray 100 years, 200 years. - Name the years that passed before the first stroke. What century has it been? (1st century) - So, when the year 100 ended, the first century ended. Then the second century began. - Name the years that passed from the first to the second stroke. What century has it been? (2nd century) - Now let's show a part of the ray that covers the next centuries to us: (Slide 14) - Which century will end on December 31, 1900? (19th century) - And December 31, 2000? (20th century) - What century began on January 1, 2001? (21st century) - So we wrote down the date correctly, and there is no mistake. It's just that the 21st century is just coming and we cannot say that 2100 years have passed already. - Look at the picture and name the century for each highlighted year. (Slide 15) Physical education "Clock" - turns with the eyes to the left and to the right, without turning the head. "Pendulum" - tilts of the body to the right - to the left "Wheels" - circular movements with arms bent at the elbows and put to the shoulders. "Alarm clock" - clapping over the head. "Spring - squats "The clock goes on - it goes, but it won't leave the place ..." - walking on the spot. IV. Consolidation of the studied material- Open the textbooks on page 55. We carry out assignments No. 280-283 (orally) Work on the timeline No. 284 (work in rows) V. Knowledge test (independent work)1 ... Convert time units: 48 h \u003d… day 8 h \u003d… min 120 min \u003d… h 180 min \u003d… h3 years \u003d… month. 36 months \u003d… Years 60 months \u003d… Years 2 years \u003d… month 5 min. \u003d… From 4 min. \u003d… S600 s \u003d… min. 2 days \u003d… h Children do work in a notebook. 2. On the blackboard: - Determine the century by year: The opening of Moscow University: 1755 -… century. Victory in the Great Patriotic War: 1945 -… century. Consolidation of the studied material1 ... Decipher proverbs and sayings: (Slide 16) Hundred live years , hundred years study. I have time, and have fun 60 minutes. 2 ... From the "Guinness Book of Records" (Slide 17) Vi. Lesson summary. Reflection- Do you remember the lesson? - What unit of time did we meet in the lesson? - What is the 1st century? (Slide 18) - With what mood are we leaving the lesson? Vii. HomeworkPage 55 No. 285, No. 287 (2) (Slide 19)

Time units

Year- a period of time approximately equal to the period of the Earth's revolution around the Sun. Distinguish the year:

stellar (sidereal)- corresponding to one apparent revolution of the Sun in the celestial sphere relative to fixed stars, equal to 365.2564 solar mean days;

tropical- between two successive passages of the center of the true Sun through the point (average) of the vernal equinox, equal to 365.2422 average solar days;

anomalistic- between two successive passages of the center of the Sun through the perigee of its visible geocentric orbit, equal to 365.2596 solar mean days;

draconic- between two successive passages of the Sun through the same (ascending or descending) node of the Moon's orbit on the ecliptic, equal to 346.62 mean solar days;

lunar- (12 synodic months), equal to 354.3671 average solar days;

julian calendar (old style)- equal to 365.2500 average solar days;

calendar Gregorian (new style)- equal to 365.2425 average solar days.

Month- a time interval close to the period of the Moon's revolution around the Earth. Distinguish the month:

synodic- the period of the lunar phase change, equal to 29.5306 average solar days;

stellar (sidereal)- the time of a complete revolution of the Moon around the Earth relative to the stars, equal to 27.3217 average solar days;

draconic- between two successive passages of the Moon through the same orbital node, equal to 27.2122 mean solar days;

calendar- does not depend on the phases of the moon, lasts from 28 to 31 days.

Day:

ephemeris,equal to 24 hours \u003d 1440 minutes. \u003d 86400 s .;

solar- the period of rotation of the Earth relative to the Sun or the time interval between two successive lower culminations of the Sun. The duration of true solar days throughout the year varies from 24 hours 03 minutes. 36 s to 24 h 04 min 27 p. sidereal time;

average solar- the average duration of a sunny day per year, equal to 24 hours 03 minutes. 56.5554 s. sidereal time;

stellar (sidereal)- the period of rotation of the Earth around its axis relative to the stars or the time interval between two successive upper culminations of the vernal equinox, equal to 23 hours 56 minutes. 040905 p. average solar time.

Hour\u003d 1/24 days \u003d 60 minutes \u003d 3600 s.

Minute\u003d 60 s \u003d 1/60 h \u003d 1/1440 days.

Second:

atomic (reference)- equal to 9192631770 periods of radiation corresponding to the transition between two hyperfine levels of the ground state of the cesium-133 atom;

ephemeris- equal to 1 / 31556925.9747 of the tropical year.

This text is an introductory fragment. From the book Encyclopedic Dictionary (EY) author Brockhaus F.A.

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