Teaching Strategies, Tactics, and Methods

Freshwater habitat facts

Looking at pictures of Earth from space, it seems like it is covered in water. It’s everywhere! Even though 70% of the planet is covered in water, only about 3% is fresh. That means we can drink, bathe, or use it for farming.

Clean, fresh water is a luxury in many parts of the world. But, without clean, fresh water, people can quickly become will. Which shows how essential freshwater habitats are.

What are they?

A Freshwater habitat definition is any body of water with a very low salt content. This habitat makes up less than 0.01% of the planet’s surface but supports over 100,000 species. That includes fish, worms, frogs, newts, birds, mammals, and amphibians.

Freshwater habitats are places with lots of water and plant life. They are found in three types, ponds/lakes, rivers and streams, and swamps/wetland areas. Different animals and plants prefer each type.

Where are they?

Ponds and lakes can be found worldwide, from Canada to Peru and China to Spain. They form where the ground is lower and can collect water. Likewise, rivers run worldwide; 177 ‘large’ rivers run throughout the Earth (including the Nile and the Amazon Rivers).

Two-thirds of the world’s freshwater is locked in glaciers at the North and South Poles. We cannot use this water in such a harsh environment.

Types of freshwater habitat

Freshwater habitats have a very low salt content compared to the oceans and seas. Often, freshwater rivers will eventually run into the sea, where the water is made salty. A habitat definition for freshwater habitats would include three types:

Ponds and lakes

Pounds and lakes are called lentic ecosystems, meaning they have still or standing waters, not moving like rivers or streams.

The temperature of lakes can change depending on where they are and what time of year it is. In tropical areas, the lakes have a fairly constant temperature but get much colder as you go deeper into the water. Lakes in the Northern Hemisphere can be very cold or much warmer, depending on the season. It affects the type of wildlife that will live in it.

What animals live in freshwater? – Ponds and lakes

Ponds and lakes are home to much fascinating wildlife, including plankton, crayfish, frogs, turtles, fishes, otters, and many species of birds. Some of the animals that live in freshwater ponds and lakes are:

• Aquatic Salamander

The Aquatic Salamander, also known as the Axolotl, is a type of reptile found worldwide but most commonly in ponds and lakes along the Atlantic coast. These creatures live on the bottom of lakes and ponds, where their carnivorous diet consists primarily of insects, worms and snails, spiders, and slugs.

• Bass

This type of fish can be found living in many different types of freshwater environments worldwide. Like Salamanders, they tend to live and feed down at the bottom of the water and enjoy hiding among rocks and weeds. However, Bass are omnivorous and are not picky about what they eat. These fish will eat almost anything, from rubbish thrown into the water to small creatures and plants.

• Crayfish

Crayfish live in a bunch of different habitats around the world. These crustaceans live in streams, rivers, ponds, lakes, marshes, and swamps. In terms of diet, crayfish eat a lot of dead animal carcasses, as well as a range of plants, insects, and other invertebrates. Strangely, crayfish are cannibalistic and have been known to eat their species.

Rivers and streams

Rivers and streams are often called lotic ecosystems, meaning they have flowing water. Unlike lakes, this biome can vary drastically in size. From tiny trickling streams in woodland areas to mile-wide rivers that travel thousands of miles.

Lots of things can affect how a river develops:

• Flow: this is how strong the flow of the river is and how much water moves through the river.
• Light: this affects the types of animals and plants that will live in or near the water.
• Temperature: If a river moves from a hot to a cold region, this will affect the types of animals in each section.

What animals live in freshwater? – Rivers and streams

Rivers and streams are teeming with wildlife, some of which you would expect and some that will come as more of a surprise. Some of these animals live in freshwater some of the time and spend the rest of their lives on land. However, some animals spend their entire lives in the water.

Some of the animals that live in freshwater rivers and streams are as follows:

• Otter

The otter is one of the most common freshwater animals in the United Kingdom. These cute little creatures were, at one point, at risk of extinction in the UK as a lot of their habitat was destroyed during the Industrial Revolution. However, after many conservation efforts, otters can now be found in rivers and streams throughout the country.

Otters are amazing predators, with fish being their choice of prey. Their genetic makeup allows them to be super-efficient swimmers and fish hunters. However, unlike a lot of other mammals that live in water habitats and eat fish, otters aren’t great at holding their breath underwater, and so can only dive for 30 seconds,

• Beaver

Another vital figure in the British rivers and streams is the beaver. Like otters, beavers were once at risk of extinction because they were heavily hunted for their many natural assets, including their fur and scent sacs. Thankfully, the number of beavers in Britain has slowly but surely been increasing.

Regarding habitat, beavers build great dams, which greatly benefit the surrounding wildlife and environment.

• American Alligators

American alligators can be found in the South-Eastern regions of the United States, particularly in the freshwater rivers, swamps, and marshes of Florida and Louisiana. Alligators are fantastic swimmers thanks to their webbed feet and strong tails that help them move through the water. Unfortunately, they are also famously fierce predators with sharp teeth and strong jaws. Their diet consists primarily of fish, invertebrates, frogs, birds, and mammals.

American alligators are one of the biggest animals that live in freshwater, growing between 3 meters and 4.5 meters long and weighing around 453 kg.

• Freshwater Eel

This scary-looking creature, also known as the American eel, has an olive-green/brown body and an almost snake-like appearance. This animal lives in freshwater rivers. Female freshwater eels can grow up to 90 cm, and males only grow to around 46 cm. These eels journey from the Gulf of Mexico up the Mississippi River to Minnesota, where they reproduce. When they’re not on the move, freshwater eels reside in large streams with muddy floors and many objects to hide in throughout the day.

River plants vary wildly depending on how fast the river or stream moves.

Wetlands biome

The wetland biome is a combination of both still water and land. You can think of it as land that has become so saturated with water that it can’t soak into the ground anymore and forms pools on the surface.

Wetlands include bogs, swamps, and marshes. They are often near large lakes or rivers (which can be their water source). Although they play an essential role in nature, wetlands can prevent flooding from rivers like the River Nile. They can also purify water as it moves through the soil and rocks.

What animals live in freshwater? – Wetlands biome

Loads of amazing mammals, birds, fish, amphibians, and more can be found in wetlands worldwide. Some animals that live in freshwater wetlands include frogs and newts, reptiles, alligators, and deer. Some other wetland creatures are:

• Bats

Eighteen species of bats can be found in the wetlands of the United Kingdom. Bats feed primarily on insects, which the wetlands have in heaps. They fly 2 to 10 meters above the ground, scouring the earth for food.

• Cranes

Cranes are another type of animal that can be found in wetlands. These huge birds are hard to miss as they are loud, friendly creatures. They have a pretty varied diet, consuming plants like seeds, nuts, acorns, leaves, berries, and fruit, as well as a range of animals, including insects, birds, reptiles, mammals, snails, frogs, and more.

Wetland plants can grow entirely underwater or float on top of the water.

Freshwater habitat facts

• Even if a river or stream dries up, some animals might continue living there by burrowing into the ground until the water returns.
• Scientists that study freshwater habitats are called Limnologists.
• The largest lake in the world is known as the Caspian Sea.
• The longest river in the world is the Nile River.

Tangrams originated in China over 200 years ago. Mathematical puzzles take advantage of the simple concept of using basic shapes to create larger or more intricate shapes and objects. Traditionally, the Chinese puzzle was a square divided into seven pieces called Tans. Each of the pieces had a different shape, including:

• 2 large right triangles
• 1 medium-sized right triangle
• 2 small right triangles
• 1 small square
• 1 parallelogram

You have to solve the puzzle by arranging the pieces (Tans) correctly to get them to fit back into a perfect square. They also came in patterns arranged into a rectangle or an equilateral triangle.

The best part about tangrams is that you can get creative with them. After taking the original shape apart, you can flip them, turn them, and rearrange them into many unique and dynamic shapes. Some of the most fascinating and creative builds turn tangram puzzles into animals, everyday objects, or rockets!

How Do Tangram Puzzles Work?

To solve a tangram puzzle, students must utilize their visual and fine motor skills together. At the same time, looking and observing to see how the pieces fit together and if the setting seems correct. Problem solving also occurs as students notice something that doesn’t seem right and aim to fix it.

Teaching Spanish numbers

Here we’ll break down Spanish numbers from 1 to 100 in handy bite-sized tables perfect for young children learning Spanish numbers at school or home. Check out the resources linked after each table; experienced educators have designed them to help all Spanish teachers feel confident and knowledgeable in their lessons.

List of Spanish numbers 1 to 20

Number	English	Spanish
1	one	uno
2	two	dos
3	three	tres
4	four	cuatro
5	five	cinco
6	six	seis
7	seven	siete
8	eight	ocho
9	nine	nueve
10	ten	diez
11	eleven	once
12	twelve	doce
13	thirteen	trece
14	fourteen	catorce
15	fifteen	quince
16	sixteen	dieiséis
17	seventeen	diecisiete
18	eighteen	dieciocho
19	nineteen	diecinueve
20	twenty	veinte

In maths, addition stories are word problems, where an additional sum is laid out in sentences for children to decipher and solve. It helps learners to understand how addiction works in real-world situations by putting it into context and allows children to identify where the maths lies in a real-life scenario. It can help them find new meaning and importance in their school work – we all remember complaints from our school days about the uselessness of what we were learning! Silence those claims with some cool additional stories.

Addition stories are great for younger learners who are practicing simple maths. They frame sums in understandable ways, illustrating them in a way children can wrap their heads around. They also help build literacy skills by providing examples of coherent, syntactically correct sentences. Learning by example is one of the main ways young children absorb information, which is great for improving their writing.

Examples of additional stories

Max ate five biscuits in the morning. He ate four more biscuits in the afternoon. How many biscuits did he eat throughout the day?

Learners must extract the correct information from the word problem to determine the sum. They’ll realize that if they want the total of Max’s biscuits, they need to add the number he ate in the morning to the number he ate in the afternoon. So, the sum is:

5 + 4 = 9

or

Sarah has twelve apples. She buys twelve more. How many apples does Sarah have now?

Again, children will extract the correct information from the word problem – in this case, the twelve apples Sarah already had and the additional twelve she bought. So the sum is:

12 + 12 = 24

From here, children can work out the sum as they normally would, for example, by using the column method or a number line.

Converting numbers: digits to words

One of the benefits of addition stories is that children get a chance to practice converting between digits and worded numbers; this is an essential practice that can help them recognize numbers in either form and the relationship between the worded and digital iterations. In addition, this helps set them up well for life when they encounter numbers in both forms.

Story Problems

The next step, along with other stories, is story problems. Whereas addition stories always feature an addition sum at their heart, story problems could feature any operation – addition, subtraction, multiplication, or division. Again, learners will be required to read the problem and decide which operation to use, which they’ll put into practice to solve.

Formative assessments are regular, informal assessments that teachers use to assess student understanding and inform teaching strategies. The ultimate goal is to collect detailed information that can be used to improve instruction and student understanding while it’s happening. Read about formative assessments in this dedicated Teaching Wiki, including the thumbs-up formative assessment.

What does formative assessment mean?

Formative assessment in the classroom means the teacher monitors pupils’ learning by providing regular and timely feedback on what they’ve done well and what they need to improve on.

It can take various forms, from informal quizzes to verbal feedback on a piece of work. To be effective, formative assessment must occur daily during teaching and learning. It’s conducted to help teachers decide how to develop student understanding further.

One commonly used formative assessment method is What Well Well? (WWW) and Even Better If? (EBI). This feedback means that pupils know what they’ve achieved to date and what they need to do next to progress in their learning.

Formative assessment is sometimes referred to as assessment for learning and usually involves diagnostic testing of some kind; this allows the teacher and the pupil to identify gaps in the pupils’ learning and then target those gaps by adjusting their planning sequences of learning to address those gaps. Depending on the subject and topic, this might involve revising previously taught concepts, practicing particular skills, or extending existing knowledge.

Formative assessment takes place in the run-up to a summative evaluation like an end-of-topic test, meaning that it is constructive in the way the results are used rather than the style of the assessment itself.

What’s the difference between formative and summative assessments?

Another way of explaining what formative assessment means is by explaining the differences between formative and summative assessment.

Summative assessment ‘sums up’ learning at the end of a set period of time, such as a term. It will also be linked to specific learning aims in the Australian Curriculum.

Summative assessments for many subjects take the form of end-of-topic tests. Depending on the subject and topic, they can be in a variety of forms, such as:

• a task;
• a written test;
• a conversation;
• or an observation.

For that reason, responses to a summative assessment could be in a range of media, including writing, photography, artwork, and audio or visual recordings. Whatever form is taken will summarize pupils learning at a given time. Typically, this data is used to record and track progress. It is also used for reporting to parents and pupils.

One good way to remember the difference between formative and summative assessments is that While a summative assessment can be seen as an ‘assessment of learning,’ a formative assessment can be seen as an ‘assessment for learning.’So let’s find out more about the differences.

Formative Assessments

Formative assessments are a method of assessing pupils. While learning is happening, rather than waiting until the end of a term or topic, this is commonly referred to as assessment for learning or AfL.

AFL evaluates the comprehension levels and learning needs of students. It is typically integrated with in-lesson learning; it doesn’t necessarily produce a score like lettered grades or numbered levels. Instead, formative assessments can help increase children’s awareness of how they learn, which can help with their sense of responsibility and independence in learning.

A task or activity is not formative unless the information it provides is used to progress learning. What makes an assessment formative is what the teacher does with the knowledge to inform their teaching on that topic.

What is a Formative Assessment framework?

A formative assessment framework provides educators with a clear structure to achieve an organized formative assessment. The framework offers both children and teachers a better focus on what children need to learn and what you, as an educator, should teach.

The formative assessment framework includes data that will help inform both learning and instruction to help structure your lessons in the best way for your class. In addition, the data from formative assessments allow educators to make an informed decision about the next steps; many studies have shown that decisions based on data are better educated than those made without. By the term ‘next steps,’ we mean the measures to put into place to help a child flourish within their learning – these decisions will be made via the formative assessment results.

The formative assessment framework usually follows this process:

• Assessing and conveying standards.
• Using the standards to collect and assess data to see where children are performing within the curriculum and current guidelines.
• The teacher then shares the feedback with students with detailed feedback.
• Based on the feedback, children will then form their formative assessment by using the comments made by the teacher to determine what they should focus on learning.

Why are Formative Assessments essential in the classroom?

Formative assessments allow children to manage activities, adjust their learning, and track their learning goals. Not only does it give educators a good amount of time to provide feedback to children regularly, but it also allows children to have their input in their learning.

Origins of Formative Assessments:

Formative assessments have been common in classrooms since the 1960s. However, they gained fresh interest following the pioneering research ‘Inside the Black Box: Raising standards through classroom assessment’ in the late 1990s.

Formative Assessment In the Classroom Examples

The ways formative assessments can be carried out are very broad. It can be as simple as teachers getting children to raise their hands if they have understood a new concept. Or an extravagant self-assessment writing exercise.

Here are some examples of formative assessments methods that are perfect in any classroom:

• Analyzing student work- either self-assessment or peer assessments
• Strategic questioning – ask students high-order questions to assess their understanding based on their answers
• 3-way summaries – students write three summaries in response to a topic of increasing length to test understanding of the content
• Sharing in groups – students discuss a topic in pairs while teachers make a note of their discussions
• Classroom polls- does everyone understand?
• One-minute papers -students write briefly about a topic, summarising their vital learning
• Spontaneous quizzes and voting exercises- see what children know about the topic through quizzes and voting exercises
• Mind maps- get children to summarise what they already know about a topic in a creative and visual way
• Summary Paragraphs- short writing exercises to see how well students have understood an idea
• Visual exercises- get children to draw something or create a collage based on your topic
• Q and A Exercises- get kids to ask questions and see which of their classmates know the answers
• Short presentations-get the children to give short presentations on the topic to show what they have learned

By trying these formative assessment methods, you’ll be able to keep track of children’s progress in a fun and less formal way. You’ll also create an approach that gives children some input with their learning by providing them with useful and consistent feedback. These methods are great to try in the classroom and accommodate both whole-class and individual assessments.

After using one of these formative assessment methods, you should follow the framework, which involves setting a task, examining children’s work, informing the teacher of knowledge and instruction, and teaching methods.

Benefits of Formative Assessments in the classroom:

As well as helping teachers to understand how well students have taken on board the topic and adjust their teaching to support them further if necessary, formative assessments have lots of benefits for helping kids learn:

• Students can use the results to improve their learning.
• The results allow teachers to adjust their teaching quickly.
• Improves children’s academic achievement and progress.
• Enhances students motivation.
• Gives children clear learning goals.
• Increases student engagement.
• Helps you deliver more targeted and personalized feedback to children.
• The results help you make an informed decision by using accurate data.
• Helps students to precisely understand the level they are working at – grades to fit with everyone, and formative assessments allow them to put their level of understanding in context.
• Reduce the learning gaps – by using the results of formative assessments to adjust teaching, you will ensure that everyone in the class gets the most out of your lessons.
• It gives children a good idea of how they are progressing and what they need to do to improve.

When did Hinduism begin?

Hinduism is one of the oldest religions in the world, and it is believed that Hinduism began as far back as 1500 BC! Furthermore, there are signs of important Hindu figures and deities such as Vishnu, Shiva, and Devi in artifacts and architecture uncovered from between 500 BC and 500 AD, so we know some form of Hinduism was around at this time.

Today, over 900 million people follow Hinduism, most of whom live in India.

Where did Hinduism begin?

Although its origins are unclear, it seems to be a mix of different beliefs, cultures, and traditions of the people who lived along the Indus River in South East Asia, near modern-day Pakistan. Hinduism is sometimes referred to as a way of life as it combines many different traditions and religious beliefs. Where Hinduism began is of little importance to Hindus, who believe that their faith is timeless.

The Hinduism Creation Story

For Hindus, there are periodic cycles of creation rather than one creation; Hinduism has many creation stories.

One story is that before time began, there was no heaven, no earth, and no space in between. In this nothingness, a cobra floated with Vishnu asleep, wrapped in its coils. A magnificent lotus flower grew from his navel. In the middle of the lotus flower sat Brahma. Vishnu commanded that Brahma create the world. Brahma split the lotus flower into the earth, the sky, and the heavens. He then made the plants and animals.

Everyone learns differently. Some students take notes in class, while others prefer to listen. Some may feel their understanding snap into place when they look at a diagram, while others need a friend to explain things; this is entirely normal. Every person’s brain is different, so it makes sense that the way we process information isn’t the same either.

Kinaesthetic learning is an example of this and refers to people who learn best through physical activity. Kinaesthetic learners are often referred to as ‘body smart’ because they’re natural doers and process information best when they can actively participate.

What are the different types of learning?

Howard Gardner (1983) came up with the theory of multiple intelligences in learning, saying that there were eight types of intelligence. These were:

1. Musical-rhythmic (music smart)
2. Visual-spatial (picture smart)
3. Verbal-linguistic (word smart)
4. Logical-mathematical (number smart)
5. Bodily-kinaesthetic (body smart)
6. Interpersonal (people smart)
7. Intrapersonal (self-smart)
8. Naturalistic (nature smart)

This idea greatly impacted how people viewed education, as it acknowledged the complexities of intelligence and validated learning in different ways.

Of course, this doesn’t mean that people could only fit into one of these categories. On the contrary, the multiple intelligences theory empowers people to think about how they learn and embrace their abilities.

How to cater to kinaesthetic learners in the classroom

In the classroom, students with high kinaesthetic intelligence may learn best when they can get tactile and hands-on. Here are a few simple strategies and examples to help support the kinaesthetic learners in your classroom.

Flashcards

The physical nature of flashcards helps kinaesthetic learners process the information they’re studying. They’re also portable, so there’s no reason why learners couldn’t use them while going for a walk or even pacing around the classroom.

Encourage movement

It could mean taking frequent breaks during a lesson to stretch their legs and boost their energy levels. In addition, teachers can support their kinaesthetic learners by giving them physical tasks to do to keep them engaged and physically active. It could be anything, from asking a student to hand out worksheets to closing the window.

Educational games

Taking part in something, even virtually, is a great way to help kinaesthetic learners process their learning. So why not take advantage of the many online educational apps and games? You could also make your games up in class to help boost energy levels. For example, hosting a class spelling bee or a maths tournament where students take turns standing and answering questions.

Give students projects to work on

Perhaps students can create something using their hands to complement their learning. Dioramas are a good example of this – along with craft activities. Or how about students writing sketches in groups on subjects they’re covering in class? Tactile and active experiences for students to focus their energy on are a great way to mix things up and channel creativity.

The vital thing to remember when planning for kinaesthetic and tactile learning is that students remember what they do and touch. So think about how to make lessons active and hands-on.

12 Days of Christmas Acts of Kindness Ideas:

You can keep your ideas simple! Encourage your family or students to brainstorm ideas or ways of showing kindness, and then you can pick these ideas out of a hat. If you’re struggling to think of ideas, we have listed some ideas to try over Christmas and some for students to complete at school.

Here are some ideas for your 12 Days of Christmas Acts of Kindness:

• Take soup or meals to homeless shelters.
• Give a compliment to everyone in your family.
• Make cookies or cupcakes and take them to a neighbor or homeless shelter.
• Offer to do someone else’s chores around the house for the day/week.
• Do something nice for a family member or friend.
• Make a Christmas card for someone.
• Go Christmas caroling as a family!
• You could shovel someone’s driveway if there’s snow.
• Donate clothing or household items that you don’t need anymore.
• Leave a gift or money to the mailman and the garbage collectors to show appreciation for their hard work throughout the year.
• Donate money to charities.
• Clear the table or kitchen after dinner.
• Wash someone’s car.
• Smile and say hello to people as you pass them. This simple act of kindness could make someone’s day.
• Make someone’s Christmas wish come true, no matter how big or small!

12 Days of Christmas Acts of Kindness ideas for your students:

• Share your food with someone.
• Make a Christmas card for someone.
• Help a classmate with their work.
• Make a “Thank You” card for your teacher.
• Offer to help someone with a task.
• Do something nice for someone.
• Make a Christmas gift! It doesn’t need to cost anything; you could draw or create a Christmas craft.
• Hold the door open for your teachers or classmates.
• Clear up a mess you didn’t make.
• If it has fallen off a peg, hang up someone’s coat or bag.
• Sharpen all the pencils in the class
• Sort out books if they’re all jumbled up.
• Donate your old books to the library.
• Tell someone a joke to cheer them up if they’re feeling sad.
• Donate old school clothes if they don’t fit anymore.
• Have a bake sale to raise money for a charity.
• Pick up garbage around the school.
• Ask your teacher if any jobs need to be done.
• Befriend new students, helping them settle into class.
• Ask someone how they’re feeling to brighten their day.

What is longitude?

Longitude lines are defined as geographical coordinates used to determine the east and west points on the Earth’s surface. It’s usually expressed in degrees and is coupled with a latitude coordinate, which determines the north and south points of a longitude line.

The north and south poles:

All the longitude lines intersect at the north and south poles; this means that if you were to go to the north pole, you could theoretically walk in a small circle and have walked through every longitudinal degree on Earth!

Longitude and time zones

There are 360 degrees of longitude and 24 hours a day.

It means that every 15 degrees longitude is a new time zone, each time zone an hour apart.

The history of longitude

Naturally, humans were keen to define longitude in Geography terms that could benefit those traveling long distances. So in 190-120 BC, Hipparchus, a Greek astronomer, tried establishing longitude and latitude as coordinates. He started by making a zero meridian that passed through Rhodes. However, his method of carrying this project to completion required an accurate clock, of which none was.

Many scientists and astronomers attempted to figure out the distance between meridian lines. Still, it wasn’t until Galileo they managed to time the eclipses of Jupiter’s moons with a pendulum clock.

However, there was still an issue with establishing longitude at sea. It wasn’t until an ordinary clockmaker, John Harrison, from England, made a device that could set longitudes while sailors were seafaring. He found that if you established the time of the location in the sea by the sun’s angle and then compared that to the time of the timezone of Greenwich (the meridian line), you can decipher the distance traveled.

What is the earth’s crust?

Don’t be confused with the crusts from a slice of toast; the crust we’re talking about here is very different and much bigger.

The “crust” describes the outermost shell of a terrestrial planet. Our planet’s thin, approximately 40 – 60km deep crust — just 1% of Earth’s mass — contains all known life in the universe.

The layers of the planet

Earth has three layers: the crust, the mantle, and the core. The crust is made of solid rocks and minerals. Beneath the crust is the mantle, primarily concrete stones, and minerals, but includes patches of semi-solid magma. At the center of the Earth is a hot, dense metal core.

How the Earth’s crust was made

Billions of years ago, the Earth started as a hot, sticky, glue-like ball of rock. The heaviest material, mostly iron and nickel, sank to the center of the new planet and became its core. The molten material that surrounded the core was the early mantle.

Over millions of years, the mantle cooled. Water trapped inside minerals erupted with lava, a process called “outgassing.” As more water was outgassed, the mantle solidified. Materials that initially stayed in their liquid phase during this process, called “incompatible elements,” ultimately became Earth’s brittle crust.

From mud and clay to diamonds and coal, Earth’s crust is composed of igneous, metamorphic, and sedimentary rocks. Forces created Earth’s crust, which continues to be shaped by the planet’s movement and energy. The Earth’s crust is divided into two types: oceanic crust and continental crust.

Tectonic plates and the crust

The Earth’s crust is broken into plates, and it was once believed that convection currents in the mantle slowly moved the crust around.

It is now thought that a mechanism called slab pull drives the movement of tectonic plates. Slab pull occurs when older, denser tectonic plates sink into the mantle at subduction zones. As these older sections of plates sink, newer and less thick sections are pulled behind. Sinking in one place leads to plates moving apart in other places.

The movement of the plates, and the activity inside the Earth, is called the theory of plate tectonics.