Period facts for kids

Period is a word that has many different meanings depending on how you use it. It can describe a specific length of time, a mark you use when writing, or even a row in a science chart. Let's explore some of the most common ways we use the word "period."

What Does 'Period' Mean?

The word "period" comes from an old Greek word meaning "a way around" or "a circuit." This gives us a clue about many of its meanings, which often involve cycles or specific lengths of time. Understanding the context helps you know which meaning of "period" is being used.

Period as a Punctuation Mark

When you are writing, a period is a small dot ( . ) that you put at the end of a sentence. It tells the reader that a thought is complete. In some places, like the United Kingdom, this punctuation mark is often called a full stop. It helps make writing clear and easy to read.

• Example: "The sun is shining today.''."

Periods in Geology and Earth's History

In geology, a period is a very long stretch of time in Earth's history. Geologists study the layers of rock to understand these periods. Each geological period often has unique types of plants and animals that lived during that time. For example, the Jurassic period was a time when many dinosaurs lived. These periods help scientists organize the vast timeline of our planet.

The Monthly Period in Biology

For girls and women, a period refers to the time every month when their body goes through a natural process called menstruation. This is a normal part of growing up and a sign that a girl's body is developing. It is part of a monthly cycle where the body prepares for a possible pregnancy. If pregnancy does not happen, the lining of the uterus leaves the body. This process usually starts when a girl is between 10 and 16 years old.

Periods as Repeating Cycles

A "period" can also mean the time it takes for something to happen and then repeat itself. This idea of a repeating cycle is important in many areas of science and daily life.

• For example, the school day has different "periods" for different subjects.

Orbital Periods in Space

In space, an orbital period is the time it takes for one object to go completely around another. For instance, the Earth's orbital period around the Sun is about 365 days, which is one year. The Moon's orbital period around the Earth is about 27 days. Scientists use orbital periods to track planets, moons, and satellites.

Periodic Functions in Math

In mathematics, a periodic function is a type of function that repeats its values at regular intervals. Think of a wave that goes up and down in a steady pattern. The "period" of the function is the length of one complete cycle of the wave before it starts to repeat. This concept is used in many fields, like studying sound waves or light waves.

Periods in Sports: Ice Hockey

In sports, especially in ice hockey, a period is one of the main parts of the game. An ice hockey game is divided into three periods, each lasting 20 minutes. There are short breaks between these periods. This helps organize the game and gives players a chance to rest.

Periods in Chemistry: The Periodic Table

In chemistry, the periodic table is a chart that organizes all the known chemical elements. Each horizontal row in this table is called a period. Elements in the same period have the same number of electron shells, which are layers where electrons orbit the atom's nucleus. The periodic table helps scientists understand how different elements behave and react with each other.

See Also

In Spanish: Período para niños