In this lesson, we will look at the units of length, square and table units of the square. Consider various units of measurement of length and square, we will find out in what cases they are used. We systematize our knowledge using the table. We decide a number of examples for the translation of one units of measurement to others.

You are familiar with various length units. What units of length are convenient to use when measuring the thickness of the match or the length of the body of God's cows? I think you called millimeters.

What units of length are convenient to use when measuring the length of the pencil? Of course, centimeters (see Fig. 1).

Fig. 1. Measurement length

What units of length are convenient to use when measuring the width or length of the window? It is convenient to measure decimeters.

And the length of the corridor or the length of the fence? We use meters (see Fig. 2).

Fig. 2. Measurement length

To measure larger distances, for example, distances between cities, use a larger than meter, a number of length - a kilometer (see Fig. 3).

Fig. 3. Measurement length

1 kilometer 1000 meters.

Express the distance in kilometers.

1 kilometer is a thousand meters, it means that the number of thousands will denote kilometers.

8000 m \u003d 8 km

385007 m \u003d 385 km 7 m

34125 m \u003d 34 km 125 m

Among the amount of hundreds, tens and units indicate meters.

It can be reasoned differently: 1 km a thousand times more than 1 meter, it means that the number of kilometers should be 1000 times less than the number of meters. Therefore, 8000: 1000 \u003d 8, the number 8 means the number of kilometers.

385007: 1000 \u003d 385 (OST. 7). The number 385 denotes kilometers, the residue is the number of meters.

34125: 1000 \u003d 34 (OST. 125), that is, 34 kilometers of 125 meters.

Read the table of length (see Fig. 4). Try to remember it.

Fig. 4. Table of length units

For measuring areas, different measurements use. The square centimeter is a square of 1 cm (see Fig. 5), a square decimeter is a square with a side of 1 dm (see Fig. 6), a square meter is a square with a side of 1 m (see rice . 7).

Fig.5. Square centimeter

Fig. 6. Square decimeter

Fig. 7. Square meter

For measuring large areas, a square kilometer is used - this is a square, the side of which is 1 km (see Fig. 8).

Fig. 8. Square kilometer

The words "square kilometer" abbreviated with the number are recorded so - 1 km 2, 3 km 2, 12 km 2. Square kilometers are measured, for example, city square, Moscow Square S \u003d 1091 km 2.

Calculate how many square meters in one square kilometer. To find the square of the square, you need to multiply the length to the width. We are given a square with a side of 1 km. We know that 1 km \u003d 1000 m, it means to find the area of \u200b\u200bsuch a square, multiply 1000 m per 1000 m, it turns out 1,000,000 m 2 \u003d 1 km 2.

Express 2 km 2 square meters. We will argue like this: as 1 km 2 is 1,000,000 m 2, that is, the number of square meters a million times more than the number of square kilometers, so I will multiply 2 per 1,000,000, we get 2,000,000 m 2.

56 km 2: Multiply 56 per 1,000,000, we get 56,000,000 m 2.

202 km 2 15 m 2: 202 ∙ 1 000 000 000 + 15 \u003d 202 000 000 m 2 + 15 m 2 \u003d 202 000 015 m 2.

To measure small areas, a square millimeter is used (mm 2). This is a square, the side of which is 1 mm. The words "square millimeter" with the number are recorded as follows: 1 mm 2, 7 mm 2, 31 mm 2.

Calculate how many square millimeters in one square centimeter. To find the square of the square, you need to multiply the length to the width. We are given a square with a side of 1 cm. We know that 1 cm \u003d 10 mm. So, to find the area of \u200b\u200bsuch a square, multiply 10 mm by 10 mm, it turns out 100 mm 2.

Express 4 cm 2 square millimeters. We will argue like this: since 1 cm 2 is 100 mm 2, that is, the number of mm 2, 100 times the number of CM 2, so I will multiply 4 per 100, we get 400 mm 2.

16 cm 2: Multiply 16 per 100 \u003d 1600 mm 2.

31 cm 2 7 mm 2: This is 31 ∙ 100 + 7 \u003d 3100 + 7 \u003d 3107 mm 2.

In life, such areas of Square as AR and Hectar are often used. AR is a square with a side of 10 m (see Fig. 9). In terms of numbers, it is written in short: 1 A, 5 A, 12 a.

Fig. 9. 1 AR.

1 A \u003d 100 m 2, so it is often called weaving.

Hectar is a square with a side of 100 m (see Fig. 10). The word "hectare" in numbers abbreviated as follows: 1 hectare, 6 hectares, 23 hectares. 1 ha \u003d 10,000 m 2.

Fig. 10. 1 hectare

Calculate how many AROs in 1 hectare.

1 ha \u003d 10,000 m 2

1 A \u003d 100 m 2, So, 10000: 100 \u003d 100 A

Now carefully consider the table of units of the area (see Fig. 11), try to remember it.

Fig. 11. Table Units Square

In the lesson, we met a new unit of length - km and units of Square - M 2, km 2, a, ha.

1. Bashmakov M.I. Nefodeova M.G. Mathematics. 4th grade. M.: Astrel, 2009.
2. M. I. Moro, M. A. Bantova, G. V. Belfyukov and others. Mathematics. 4th grade. Part 1 of 2, 2011.
3. Demidova T. E. Kozlova S. A. Tonky A. P. Mathematics. 4th grade 2nd ed., Act. - M.: Balam, 2013.

1. School.xvatit.com ().
2. Mer.kakras.ru ().
3. Dpva.info ().

Homework

1. Find the square of the square with a side of 15 dm.
2. Express: Square meters: 5 hectares; 3 hectares 18 A; 247 acres; 16 A;
3. in hectares: 420,000 m 2; 45 km 2 19 hectares;
4. in Arash: 43 hectares; 4 hectares 5 A; 30 700 m 2; 5 km2 13 hectares;
5. in hectares and arah: 930 A; 45 700 m 2.

MEASURES Lena length, measures area, measure of volume, mass measure. Three variants of multiplication table. Decimal number system

Multiplication table. Option 1

Table multiplication from 1 (units) up to 10 (ten). Decimal system

Multiplication table. Option 2.

Multiplication table Abbreviated from 2 (two) to 9 (nine). Decimal system

Multiplication table. Option 3.

Table multiplication from 1 (units) to 20 (twenty). Decimal system

Value - This is what can be measured. Concepts such as length, area, volume, weight, time, speed, etc. are called values. The value is measurement resultsIt is determined by the number expressed in certain units. Units in which the value is measured, called units of measure.

For the designation of the magnitude, the number is written, and next to the name of the unit in which it was measured. For example, 5 cm, 10 kg, 12 km, 5 min. Each value has countless values, for example, the length can be equal to: 1 cm, 2 cm, 3 cm, etc.

The same value can be expressed in different units, such as kilograms, grams and tons - these are weight measurement units. The same value in different units is expressed by different numbers. For example, 5 cm \u003d 50 mm (length), 1 h \u003d 60 min (time), 2 kg \u003d 2000 g (weight).

Measure any value - it means to find out how many times it contains another value of the same kind, adopted per unit of measurement.

For example, we want to find out the exact length of some room. So we need to measure this length using another length, which is well known to us, for example, with a meter. To do this, we postpone the meter on the length of the room as many times as possible. If it meets the length of the room is exactly 7 times, then its length is 7 meters.

As a result, the measurement of the magnitude is obtained or named number, for example, 12 meters, or several named numbers, for example 5 meters of 7 centimeters, the totality of which is called compound nominated number.

Measures

In each state, the government has established certain units of measure for different quantities. Accurately calculated unit of measure, taken as a sample, is called etalon or exemplary unit. Made exemplary meters, kilograms, centimeters, etc., on which units for everyday use are made. Units included and approved by the state are called measures.

Measures are called uniformIf they serve to measure the values \u200b\u200bof the same kind. So, grams and kilograms are homogeneous measures, as they serve to measure weight.

Units

Below are the units of measurement of different quantities that are often found in Mathematics tasks:

Weight / Mass Measures

• 1 ton \u003d 10 centners
• 1 centner \u003d 100 kilograms
• 1 kilogram \u003d 1000 grams
• 1 gram \u003d 1000 milligrams

• 1 kilometer \u003d 1000 meters
• 1 meter \u003d 10 decimeters
• 1 decimeter \u003d 10 centimeters
• 1 centimeter \u003d 10 millimeters

• 1 square kilometer \u003d 100 hectares
• 1 hectare \u003d 10,000 square meters. metram
• 1 square meter \u003d 10,000 square meters. Santimeters
• 1 square centimeter \u003d 100 square meters. millimeters

• 1 cubic. meter \u003d 1000 cubic meters. Decimeters
• 1 cubic. Decimeter \u003d 1000 cubic meters. Santimeters
• 1 cubic. Santimeter \u003d 1000 cubic meters. millimeters

Consider such a magnitude as liter. A liter is used to measure the capacity of blood vessels. A liter is a volume that is equal to one cubic decimeter (1 liter \u003d 1 cubic meter. Decimeter).

Time measures

• 1st century (century) \u003d 100 years
• 1 year \u003d 12 months
• 1 month \u003d 30 days
• 1 week \u003d 7 days
• 1 day \u003d 24 hours
• 1 hour \u003d 60 minutes
• 1 minute \u003d 60 seconds
• 1 second \u003d 1000 milliseconds

In addition, use such time measurement units as a quarter and decade.

• quarter - 3 months
• decade - 10 days

The month is accepted in 30 days, if you do not need to determine the number and name of the month. January, March, May, July, August, October and December - 31 days. February in a simple year - 28 days, February in the leap year - 29 days. April, June, September, November - 30 days.

The year is (approximately) the time during which the Earth makes a complete turn around the sun. It is customary to consider every three consecutive years to 365 days, and the next fourth is the next - in 366 days. Year containing 366 days called leap, and the years containing 365 days - simple. By the fourth year, one extra day is added for the following reason. The time of circulation of the Earth around the Sun contains in itself not exactly 365 days, but 365 days and 6 hours (approximately). Thus, the simple year is shorter than the true year for 6 hours, and 4 of the ordinary year in short, 4 true years for 24 hours, i.e. on one day. Therefore, each fourth year add one day (February 29).

On the other types of magnitude you will learn as the last study of various sciences.

Abbreviated names of Mer.

Abbreviated names of measures are taken to record no point:

Measuring instruments

For measuring different quantities, special measuring instruments are used. Some of them are very simple and are intended for simple measurements. Such instruments include a measuring ruler, roulette, measuring cylinder, etc. Other measuring instruments are more complex. Such devices include stopwalls, thermometers, electronic scales, etc.

Measuring instruments, as a rule, have a measuring scale (or briefly). This means that bar divisions are applied on the instrument, and the corresponding value is written next to each bar division. The distance between two strokes, near which the value is written, can be additionally divided into several smaller divisions, these divisions are most often indicated by numbers.

To determine what value of the value corresponds to each small division, it is not difficult. For example, the figure below shows the measuring ruler:

Figures 1, 2, 3, 4, etc. indicate distances between strokes, which are divided into 10 identical divisions. Consequently, each division (the distance between the nearest strokes) corresponds to 1 mm. This value is called price division scale Measuring instrument.

Before proceeding with the measurement of the value, the price of dividing the scale of the instrument used should be determined.

In order to determine the fission price, it is necessary:

1. Find the two nearest touches of the scale, near which the values \u200b\u200bare written.
2. The deduction from the larger value is less and the resulting number is divided into the number of divisions between them.

As an example, we will determine the division of the thermometer scale depicted in the picture on the left.

Take two strokes, about which the numeric values \u200b\u200bof the measured value (temperature) are applied.

For example, touches with notation 20 ° C and 30 ° C. The distance between these strokes is divided into 10 divisions. Thus, the price of each division will be equal to:

(30 ° C - 20 ° C): 10 \u003d 1 ° C

Consequently, the thermometer shows 47 ° C.

Measure various quantities in everyday life is permanently each of us. For example, to come in time to school or to work, it is necessary to measure the time that will be spent on the road. Meteorologists for weather prediction measure temperature, atmospheric pressure, wind speed, etc.

Today, each of us with the designation of certain measurement measures is used only by modern terms. And it is considered normal and natural. However, when studying history or when reading literary works, we often face such words as "Poky", "Arches", "elbows", etc.

And such consumption of terms is also normal, since it is nothing more than ancient measurement measures. What they designate should be known. Why? First, it is the story of our ancestors. Secondly, such knowledge is an indicator of our intelligent level.

The history of the emergence of Mer.

The development of human society was impossible without comprehending the art of the account. But this was not enough. To keep many cases, certain units of length, masses and square were needed. Their person invented in the most unexpected forms. For example, any distances were determined by transitions, or steps. Vintage measurement measures relating to human growth or clarification of the amount of tissue corresponded to the length of the finger or joint, the wise of the hands, etc., that is, everything that was a kind of measuring instrument, always being with you.

We learn about the very interesting lengths by our ancestors from the chronicles and old letters. It is both the "might of the stone", that is, his throw, and the "gun shot", and "shifting" (the range of the arrows), and much more. Sometimes the unit of measurement indicated the distance on which the cry was still heard of a particular animal. It was a "cock cry", a "bobby roar", etc. An interesting measure of the length existed among the peoples of Siberia. She was called "Buka", and I meant that the distance in which the horns of the bull merged into one of the person visually in one way.

From the chronicles that came to us, we can conclude that the old measurement measures in Russia appeared in 11-12 centuries. These were such units like verst, soot, elbow and span. However, in those days, a person invented ways of determining the length were still extremely unstable. They differed somewhat depending on the principality and constantly changed over time.

From the chronicles of the 13th and 15th centuries, we learn that the old measures for measuring bulk bodies (as a rule, grain crops) - Retain, halves, quarters, and amines. In 16-17 centuries. These terms disappeared from everybody. The main measure of bulk bodies from the specified period becomes a quarter, which approximately corresponded to six pows.

In a number of documents, the era of Kievan Rus is found the word "spool". This weighing unit had the same distribution as Berkhets and Pood.

Determining length

Ancient measurement measures of physical quantities did not differ in particular accuracy. The same applies to the definition of the length of the steps. Such a unit was used in ancient Rome, ancient Greece, Persia and Egypt. Human step, the average length of which is 71 cm, determined distances even between cities. Such a unit is used in our time. However, today special instruments pedometers are determined not the distance, but the number of steps covered by man.

The length of the length that was used in the countries of the Mediterranean, served such a unit as stages. The mention of it can be found in the manuscripts dated the first millennium BC. e. The stages were equal to that distance that a man in a calm pace could pass from dawn until the solar disk fully appears above the horizon.

With the development of society, larger quantities were needed. In this regard, an ancient Roman mile appeared, equal to 1000 steps.

Vintage measurement measures of the length of various peoples differed from each other. So, Estonian sailors were determined by tubes. It was the path that the ship was held during the time of smoking completely naked tobacco tube. The same measure of the length of the Spaniards was called a cigar. The Japanese determined the distance "horsepop shoes". It was a way that could pass the animal to the full abrasion of the straw sole, which replaced the horseshoe.

Major values \u200b\u200bto determine the length in Russia

Recall the proverbs with old measurement measures. One of them is familiar to us since childhood: "From the pot two tops, and already a pointer." What is such a length of length? In Russia, it was equal to the width of the index and middle fingers. At the same time, one vertex corresponded to one Sixteenth Arshina. Today, this value is 4.44 cm. But the Russian antique measurement measure - nail - was 11 mm. Taken four times, it was equal to one handle.

In Russia, some of the old measurement measures were used in connection with the development of trade relations with other countries. So the magnitude called by Arshin appeared. This is the name from the Persian word "elbow". In this language, it sounds like "ARSH". Arshins came, equal to 71.12 cm, together with merchants from distant countries that brought Chinese silk, velvet and Indian pass.

Measuring the fabric, the eastern merchants pulled it on her hand to the shoulder. In other words, they measured the goods by Arches. It was very convenient, because such a measuring device always was with him. However, the cunning merchants were looking for quarcesmen with hands shorter, so that Arshin accounted for smaller fabric. But soon it was put an end. The authorities introduced a stateless Arshin, who had to use everything without exception. They turned out to be a wooden line, which was manufactured in Moscow. Copies of such a fixture were sent throughout Russia. And in order for no one to do not smear and shorten Arshin, the ends of the line fell as iron, on which the state stamp was stamped. To date, this unit is no longer used. However, the word denoting such a magnitude familiar to each of us. Proverbs with old measurement measures are narrated about him. So, about the perceptive person they say that he "sees underground for three ARSHIN."

What else did the distance determine the distance?

There are other vintage length measurement measures. These include the soot. The mention of this term is first found in the "Word about the beginning of the Kiev-Pechersk Monastery", dating from the 11th century. And there were two varieties of soy. One of them is a masculine, equal to the distance between the tips of the middle fingers, stretching in different directions. The value of ancient measurement measures of this type was equal to 1 m 76 cm. The second type of plant is oblique. It was the length of the shoe heel on the right foot to the tip of the middle finger left hand stretched up. The magnitude of oblique plantation was approximately 248 cm. Sometimes this term is mentioned when describing a man of the heroic physique. It is said that he has a silent sage in his shoulders.

Vintage Russian measures for measuring large distances - field or verst. The first mention of these values \u200b\u200bare found in the manuscripts of 11 V. The length of the vests is 1060 m. And initially, this term was applied to measurerable lands. He meant the distance between the turns of the plow.

Vintage measurement measures of the values \u200b\u200bwere sometimes a joking name. So, since the reign of Alexei Mikhailovich (1645-1676) of a very high person began to be called not to forget this humatic term and today.

Up to 18 V. In Russia, such a unit of measurement was used as partial verst. She measured the distance between the borders of the settlements. The length of this vests was 1000 seedlings. Today it is 2.13 km.

Another old measure of the length in Russia was a span. Its value was approximately a quarter of ARSHIN and was equal to about 18 cm. Existed:

- "Little Pant", equal to the distance between the tips of the elongated index and thumbs;
- "Big Poor", equal to the length between placed by large and middle fingers.

Many proverbs about vintage measurement measures indicate us for this value. For example, "Seven spans in the forehead." So they talk about a very intelligent person.

The smallest antique unit of length is the line. It is equal to the width of wheat grain and is 2.54 mm. Until now, time plants are used by such a unit of measurement. Only the size is accepted by Swiss - 2.08 mm. For example, the magnitude of the male clock "Victory" is 12 lines, and the female "Zarya" - 8.

European units of length

From the 18th century Russia significantly expanded its trading relations with Western countries. That is why there was a need for new measurement measures that could be compared with European. And then Peter I conducted a metrological reform. His decree in the country has introduced some English values \u200b\u200bfor measuring distances. These were feet, inches and yards. Especially great distribution, these units received in shipbuilding and on the fleet.

According to the existing legend, the yard was first determined in another 101. It was a magnitude equal to the length from the Nose of Heinrich I (King England) to the tip of the middle finger his hand stretched in a horizontal position. Today it is 0.91 m.

Foot and yard are old measurement measures, closely related. The "FOOT" from the English word "is a foot, this value is equal to one third of the yard. Today Foot is 30.48 centimeters.

From the Dutch word denoting the thumb, received its name such a unit of measure as inch. What was the initially measured this distance? It was equal to the length of the three dried barley grains or a thumb phalange. To date, one inch is 2.54 cm and is used in determining the internal diameter of automotive tires, pipes, etc.

Streamlining of the system

In order to ensure the ease of transition from one units of measurement to others, special tables were published in Russia. On the one hand they brought old measures. Units of measuring foreign origin, which corresponded to the Russians were placed through the sign of equality. These same tables and those units that should have been applied in the country were also listed.

However, confusion with the system of measures in Russia did not end. In different cities used their units. The end of this was laid only in 1918, when Russia moved to the metric system of measures.

Measurement volume

A person needed to measure bulk physical quantities and liquids. For this, he began to use everything that he had in everyday life (buckets, vessels and other tanks).

What vintage took place in Russia? Bulk bodies Our ancestors measured:

1. Octifynik, or amid. This is an old unit equal to 104,956 liters. A similar term was applied to the square, which was 1365,675 square meters. For the first time, Oshmina is mentioned in documents 15 V. It was widely used in Russia because of its practicality, as there was a volume of two times smaller than a quarter. There was even a certain standard of such a measure. It was a container to which Iron rowing was attached. The grain was poured into such a measured ointment with the top. And after, with rowing, the contents of the form struck to the edges. Samples of such tanks were made of copper and sent throughout Russia.

2. Shack, or kadue. These measuring tanks were distributed in 16-17 centuries. In later periods they met extremely rarely. Okov was the main measure of bulk bodies in Russia. Moreover, the name of this unit happened from a special barrel (tubs), which was adapted for measurements. The measuring capacity from the top was tightened with a metal hoop that did not give the capabilities to the cutes to cut her edges and sell a smaller amount of grain.

3. Quarter. This volume measure was used to determine the amount of flour, croup and grain. In everyday life, a quarter was widespread, as there were more practical dimensions (1/4 of the Okova). Such a unit of measurement in Russia was used from 14 to 19 centuries.

4. Honey. This ancient Russian measure, used for bulk bodies, was 5-9 pounds. Some researchers believe that the word "Kul" once indicated "fur". This term was used for extended animal leather coarse. Later, such tanks began to produce from woven materials.

5. buckets. Such a measure, our ancestors determined the amount of liquid. It was believed that 8 mugs are placed in the trading bucket, the volume of each of which is 10 chambers.

6. Barrels. A similar unit of measurement Russian merchants were used when selling wines to foreigners. It was believed that in one barrel contained 10 buckets.

7. Korchagami. This big clay pot found its use when measuring the volume of grape wines. For different parts of Russia, Korcaga ranged from 12 to 15 liters.

Weight measurement

Ancient Russian system measures included and units for measuring the mass. Without them, trade activities were impossible. There are various vintage mass measurement measures. Among them:

1. Spool. Initially, this word meant a small gold coin, which was a unit of measurement. Comparing its weight with other precious products, determine the purity of the noble metal, from which they were made.

2. PUD. This unit of weight was equal to 3840 spools and corresponded to 16,3804964 kg. Even Ivan Grozny prescribed to weigh any product only in Powers. And from 1797, after the release of the law on measures and weights, spherical weights began to produce, corresponding to one and two pushes.

4. Share. This unit of measurement in Russia was the smallest. Its weight was 14,435 mg, which could be compared with 1/96 spool. Most often, the proportion was used in the work of mint.

5. Pound. Initially, this name was called "hryvnia". Its value corresponded to 96 spools. Since 1747, the pound becomes used until 1918.

Square measurement

Some standards were invented by our ancestors and to determine the magnitude of land plots. This is ancient measurement measurement measures, including:

1. Square vest. Mention of this unit equal to 1,138 square meters. kilometers, occurs in documents dated 11-17 centuries.

2. Tin. This is an old Russian unit, the value of which corresponds to 2400 square meters. meters of arable land. To date, the tithing is equal to 1,0925 hectares. This unit is used from 14 V. She was known as a rectangle, the sides of which were 80 to 30 or 60 by 40 sages. Such a tith was considered the government and was the main one-hand meter.

3. quarter. This arable land was the unit that had half a decade. Known a quarter from the end of the 15th century, and its official use continued until 1766, this unit received from the size of the square, on which the rye could be seeded in the amount of ¼ of the volume of Cadi.

4. Soke. This unit of measurement of the area was used in Russia from 13 to 17 centuries. Used it for applying. Moreover, several types of soy were distinguished, depending on the area of \u200b\u200bthe best lands. So, such a unit was:

A servant containing 800 quarters of a good quality plowing;
- church (600 quarters);
- Black (400 quarters).

In order to find out how much sowing is in the Russian state, the censuses of supply lands were carried out. And only in 1678-1679. This unit area was replaced by the yard.

Modern use of vintage measures

On some units of determining the volume, area and distances that our ancestors used widely, we know today. So, in some countries, the length is still measured by miles, yards, feet and inches, and a pound and a spool use in cooking.

However, most often the vintage units are found in literary works, historical stories and proverbs.

At first glance, in the system of length measures, mass, etc. There is nothing complicated, however, for many schoolchildren, the translation from one measure to another is very difficult. Part of the children and after elementary school it is not possible to correctly relate, for example, a decimeter with a millimeter, or a hectometer with a cubic meter.

However, without clear knowledge of the system of measures is currently not to live, with measurements of one or another, people face daily and several times.

Length measurement units in tables

How is one to another without errors? One of the most effective ways to study the lengths of length or weight are tables, it is also recognized by teachers, and parents, and the students themselves.

Competently selected pictures of length measures clearly explain the schoolboy the dependence of one unit from the other. The most useful table is the one in which measures of magnitudes from the most small gradually increase, that is, a schoolboy sees that, for example, 1000mm \u003d 100cm \u003d 10 dm \u003d 1 m, especially if each value is displayed as a pattern.

Looking at the table, most of the schoolchildren, begins with a simple learning of the dependencies of certain quantities, however, quite soon comes to understanding: the student is aware that the meter contains, for example, 100 centimeters, or 1000 millimeters, but the decimeters - only 10. Good The help of this moment will be a large line, so that the learned numbers can be correlated with a real length and is remembered best.

For what you need various units of length

Some parents are asked why it is necessary to operate with various length units? Children are confused in centimeters-decimeters, and adults sometimes cannot explain to them, what value is greater and how many times.

The answer to this question does not have to look for a long time. Which units of length is convenient to measure the thickness of the match or the body of God's cow? Of course, in millimeters. In what units of length is convenient to measure the length of the handle or pencil? In centimeters.

If you need to measure the width or length of the window, the convenient unit will be decimeters. For the length of the fence, the optimal option will be meters. For the distance between cities - kilometers, for the distance between the continents - also kilometers, as it is the largest among the magnitude of lengths.

Very often, the task is given to the task - to express the length given in meters or decimeters, in millimeters or kilometers, or vice versa. It is not difficult to do this, if you know the ratio of lengths by heart, or use the assistant table. It is much more difficult to translate the volume of volume - liters into square decimeters or vice versa, but also for the measures of volume there are its tables, successfully helping to assimilate the relationship between values.