How to explain the Earth to children
Il 22th April every year we celebrate World Earth Day, a precious opportunity to photograph the state of health of our planet, to bring out critical issues and support globally the actions we can take to protect the Earth and to change the things, starting from our daily life. In many schools, Earth Day allows teachers to propose new materials and topics of study on our planet, to have concept maps developed and to study how the Earth is made. But how to explain the Earth to children? Here are some tips.
In this article
- Planet Earth: how it is made
- Conceptual map
- Explanations for primary school children
Planet Earth: how it is made
La Land is one sferoid offer (i.e. it has a spherical shape but not perfectly round) and is the third of eight planets that make up our solar system and is the only one that can support life. The Earth is estimated to have 4,54 billion years: in northwestern Canada, ancient rocks of about 4,03 billion years have been discovered.
The highest point on Earth is the Monte Everest, in Nepal, which rises 8.850 kilometers (29.035 ft) in the Himalayan mountains of Asia.
The Earth is a place rich in water: about 71% of the earth's surface is covered with water, and the oceans contain about 96,5% of all Earth's water. Water is also present in the air as water vapor, in rivers and lakes, in polar caps and glaciers, in the ground as soil moisture and in aquifers, and also in living beings that inhabit the planet.
The outer layer of the Earth is made up of large moving pieces called plaques. All the earth and water on the planet are found on these plates which are made of solid rock. Below the plates is a weaker layer of partially molten rock on which the plates are constantly moving.
When plates move, they can interact with each other in different ways:
- they can slide next to each other
- they can collide with each other and in this case the edge of a slab can end up under the edge of another and destroy itself, or the collision between the two edges can create a new mountain
- when, on the other hand, the plates move away from each other, the molten rock below rises and as it rises it cools, forming a new crust.
Impossible to dig a tunnel in the center of the earth (as Jules Verne had imagined) to go and see what it is, but modern technologies and tools available to scientists have made it possible to use seismic waves to understand that the Earth is made up of layers , like an egg. The structure of the Earth is made up of three concentric layers: the crust, mantle and core.
- Earth's crust: the crust is the outermost part of the planet, the one on which we live and walk. It has a thickness ranging from 6 kilometers (under the oceans) up to 70 (under the continents). The crust is separated from the upper mantle by a zone known as the "Moho discontinuity".
- Upper cloak: it is a solid layer in continuous movement that has a thickness of about 650 kilometers. Its movement can give rise to volcanic eruptions and earthquakes.
- Lower mantle: it is composed of molten rocks and there is a temperature of about one thousand degrees centigrade, for a thickness of 2200 kilometers. The lower mantle is separated from the inner core by an area called the "Gutenberg discontinuity".
- External core: the structure of the external core, surrounded and protected by a mantle of heavy rock, mainly silicates, is mainly composed of molten nickel and iron found in a liquid state. It is about 2.250 thick and an area called the "Lehmann discontinuity" separates it from the inner core.
- Inner core: we have arrived here at the true center of the Earth which is about 5.100 kilometers deep and there is a very high temperature (6.000 ° C). To keep solid the alloy of iron and nickel of which the inner core is composed is the very strong pressure inside it.
If we want to help children make one concept map on planet Earth we can find many useful resources on this site
The concept map can be very useful for summarizing and schematizing the movements of the Earth on itself and around the sun (motion of revolution and motion of rotation), but also to draw the very structure of the planet inside.
Explanations for primary school children
For primary school children we can make a real one Earth identity card:
- size and history: the Earth is located about 150 million km from the Sun and was formed 4,57 billion years ago;
- the earth's rotations: our planet takes 365,256 days to make a complete circle around the sun, at the same time the Earth rotates from west to east every day, taking 23 hours, 56 minutes and 4,091 seconds to make a complete revolution;
- la Land it is composed for the most part of water;
- on the earth's surface the outer layer is composed of plaques tectonics which are continuous motion;
- at his internal the earth is made up of a crust, mantle and core;
- l'terrestrial atmosphere it is a mixture of gases that surround the planet and of which oxygen constitutes 20%.