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Lesson 1: What Living Things Need

We have been building upon this topic from Grade 1 and at this point we will provide some more details as you start your Grade 3 Science classes.

Plants and animals are living things (also called Organisms and they have the following properties:

Living Things Grow: All organisms use energy to grow. To grow means to change with age. A young sunflower plant is small and green. Over time, it grows taller and its stem grows harder.

Living Things Respond: When its cold, you shiver to generate heat to warm the body. When its hot, you sweat so as to release heat away from the body. When a plant is in a shade, it bends toward sunlight. When a bird sees a cat and senses danger and flies away. When fall comes and the weather gets colder, trees shed their leaves and prepare for winter.

Living Things Reproduce: To reproduce means to make more of one’s own kind. An apple tree reproduces by making apple seeds. The seeds can grow into new apple trees. Chicken reproduce by laying eggs. Young chicks hatch from the eggs.

Nonliving things are all around you. Rocks, soil, and water are nonliving things that come from nature. Cars and roads are nonliving things made by humans. They do not grow, respond or reproduce.

Living things get everything they need to survive from their environment. An environment is all the living and nonliving things that surround an organism.

Living things need food, water, air and space to survive.

All living things are made up of cells. Cells are very small, they cannot be seen with just your eyes. You need an instrument called Microscope to observe cells. A microscope is a tool that makes small things appear larger.

Some organisms, such as Bacteria are made up of only one cell.

Lesson 2: Animals and Their Parts

Oxygen: Animals breathe to get oxygen. Many animals breathe with lungs. Lungs are structures that take in oxygen from the air. Fish get oxygen using gills. Gills are structures that take in oxygen from the water. Some animals can breathe without lungs or gills. Worms and salamanders, for example, take in oxygen through their skin.

Food and Water: Animals use various structures to obtain food and water. Birds have specialized beaks to catch worms. lions can run fast and have strong jaws to grasp their prey. dogs have shapr canine teeth to tear through meat. Cows have hard gums and lips to prevent them from being injured by the shapr blades of grasses.

Moving: Animals move in search of food, water and shelter, and away from danger. Movement can be done in various ways. Most animals use legs to move. Some have the ability to fly. Other animals, such as snakes, do not have legs and they slither on the ground.

Staying safe: Animals stay safe from danger and from extreme weather events. Some animals dig the ground and shelter there. Lizards stay under rocks. some birds build nests. Tortoises and snails move around with their shells as protection.

Lesson 3: Classifying Animals

Classifying animals to form smaller groups makes it easier for scientists to study them. One way scientists classify animals is by their structures.

Animals with backbones are called vertebrates. Tigers, dogs, eagles, people, goldfish etc are vertebrates.

Animals that do not have a backbone are called invertebrates. Insects, spiders, worms, snails etc are some examples of invertebrates.

Some invertebrates, such as insects, lobsters etc have a hard shell on the outside called an Exoskeleton.

Birds: Birds are a kind of animals that have a beak, feathers, two wings and two legs. they are built to fly, though not all of them do a good job at it.

Reptiles: Reptiles are vertebrates with a rough scaly skin. Crocodiles, snakes, turtles are some examples. Some reptiles live on land while others live in water. All reptiles breath through their lungs, so they lift their heads above water to breath.

Amphibians:

are a group of animals that spend a part of their lives in water and part on land. Frogs, toads and salamanders are examples. Most start as eggs which hatch into a fish-like stage that breaths through gills. As they get older, they grow legs and lungs and begin to live on land.

Fish: fish are vertebrates (they have a backbone). They spend their whole life in water and obtain air (oxygen) through gills. Most are covered in scales on their skin and their skin is slimy.

Mammals: mammals are a large group of diverse animals. Mammals are characterized by the presence of mammary glands that produce milk for feeding their 'babies'. Mammals have skin covered in hair or fur. All mammals breath using lungs. Some, such as dolphins and whales, live in water and rise to the surface to breath.

Lesson 4: Animal Life Cycles

Different types of animals change in different ways. Some animals are born looking like their parents. Others are not. These animals might change shape or color as they grow. They may even grow new structures. The way an animal changes with age is part of its life cycle.

Some animals change shape through a process called metamorphosis. Amphibians and most insects go through metamorphosis. Their life cycle begins with an egg. Eggs contain food that young animals need. Most have a shell that protects the animal.

Reptiles, fish, and birds have similar life cycles. Most of these animals lay eggs. Reptiles lay their eggs on dry land. Fish lay their eggs in water. Birds often build nests to protect their eggs. Most birds sit on their eggs until the eggs are ready to hatch.

Lesson 1: Food Chains and Food Webs

Living things depend on each other. They also depend on nonliving things like sunlight. Living and nonliving things that interact in an environment make up an ecosystem. An ecosystem may be a pond, a swamp, or a field, maybe large or small.

Different organisms live in different parts of an ecosystem. Fish live in the water, so the water is the fish's habitat.

A food chain shows how energy passes from one organism to another in an ecosystem. When a buffalo feeds on grass, they obtain energy from the grass, and when a lion feed on the buffalo, they obtain energy from the buffalo. energy flows from grass to buffalo to lion.

The first organism in a food chain is called a producer, these are organisms that make their own food. Green plants are examples of producers. Most producers use energy from the Sun to make their own food. This means that the energy in most food chains starts with the Sun.

A consumer is the organism that eats other organisms. All animals are consumers. A food chain may have many consumers.

Organisms that eat mostly plants are herbivores. Some animals, such as herons, eat mostly other animals. These organisms are carnivores. Animals that eat both plants and animals are omnivores.

Predators hunt other organisms for food. The organisms they hunt are prey.

A decomposer is an organism that breaks down dead plant and animal material. Decomposers put nutrients back into the soil. Some worms and bacteria are decomposers.

Since consumers can eat many types of organisms, many food chains can join to form a food web.

Lesson 2: Types of Ecosystems

Different ecosystems have different types of soils and climate conditions. Climate is the pattern of weather in a place over a long time.

Ecosystems also differ in the types of plants and animals they have. Grasslands are covered in grass while forests are filled with trees. Oceans are filled with fish that can live in salt water. Ponds are filled with fish that can live in fresh water.

A desert is an ecosystem that has a dry climate with low rainfall of less than 25cm per year. Deserts usually have hot days but temperatures reduce drastically at night. The soil in the desert is mostly sand, with very little orgnaic matter.

A forest is an ecosystem that has many trees.

An ocean is a large body of salt water. Earth has five oceans, which are all connected. These are the Atlantic, Pacific, Indian, Arctic, and Southern Oceans. The Pacific Ocean is the largest. It covers about one third of the planet. Billions of living things are found in Earth’s oceans.

A wetland is an ecosystem where water covers the soil for most of the year. Wetlands are often found along the edges of rivers, lakes, ponds, and oceans. They may have fresh or salt water.

Lesson 3: Adaptations

An adaptation is a structure or behavior that helps an organism survive in its environment.

Some adaptations help living things stay safe. For example, some animals hide from enemies by blending into their. Camouflage can also help animals sneak up on their prey.

Many desert animals, such as rattlesnakes and coyotes, are nocturnal. This means they are active at night. They sleep during the day. They come out at night when the desert is cooler.

Jackrabbits have large ears that help them to stay cool as warm blood flows through the ears and heat is lost.

Some trees lose their leaves in fall as the temperature drops. This adaptation helps trees save energy.

Some forest animals blend in by looking like other, very different organisms. This adaptation is called mimicry. Mimicry is when one living thing imitates another in color or shape.

Animals like the dormouse survive by hibernating. Hibernate means to go into a deep sleep. While hibernating, animals use less energy and do not need to eat.

Migration: Animals may migrate when their environment gets too cold or when food or water is hard to find.

Lesson 1: Living Things Change Their Environments

Every living thing changes its environment as it seeks to meet its needs to survive. A plant takes water from the soil as it grows. In this case, water is an example of a resource. We can define a resource as something that helps an organism to survive. Food, water, air, space, sunlight, shelter are examples of resources needed by living organisms.

Resources tend to be limited in availability. The ground only has enough water to support a certain volume of plants and animals. This results in the living things competing for the resources. Competition for resources means the living things that are 'stronger' and able to survive better in the environment will survive, and the weaker organisms will not be able to access the resources they need, so they will not survive.

Land itself is a reource that is also limited (scarce). As the population of people in the world increases, they compete with other living organisms for the same resources. This has resulted in people cutting down forests so as to build homes, or changing agricultural farms into malls.

People can help protect their environments. One thing people can do is practice the 3 Rs—reduce, reuse, and recycle. To reduce means to use less of something. To reuse means to use something again. To recycle means to turn old things into new things. When you practice the 3 Rs, you produce less trash and cut down on pollution.

Lesson 2: Changes Affect Living Things

Two years ago, in 2020, the world experienced the COVID19 outbreak and the pandemic that followed and changed people's lifestyle a great deal. Natural disasters such as floods and droughts, and diseases (such as Covid19) can change the environment directly or indirectly. Widfires also cause extensive changes to the environment.

Organisms respond to changes in the environment. Sometimes organisms develop adaptations that enable them to survive in the new environment. Sometimes they migrate to other regions where they can survive. And in some unfortunate cases, living organisms die when the environment changes. For example, widl fires may rsult in the death of many trees in a forest.

Let us define two more words: A population is the number of all the members of one kind of organism in an ecosystem. For example if you count the number of coyotes in Alberta, Canada. You need to define the region you are refering to. A community is all the populations in an ecosystem. Notice that a community is made up of individuals from many groups, not the same group. So a community will include the number of coyotes, wolves, foxes, deers, bears plants etc.

An organism is endangered when there are only a few living members of its kind left.

Lesson 3: Living Things of the Past

Millions of years ago, dinosaurs may have been roaming through the land that is now your town! All that is left of dinosaurs today is their fossils. Fossils are the remains of organisms that lived long ago. Many scientists think that dinosaurs became extinct after a meteor hit Earth a long time ago. A living thing is extinct when there are no more of its kind alive.

Some plants and animals are becoming extinct even today. Some scientists think that up to 100 kinds of organisms become extinct each day! In 1996 a type of mammal called the red gazelle became extinct. It was hunted too often by humans.

Many organisms living today look similar to those that lived long ago. Some modern birds resemble ancient reptiles. Eagles look very similar to flying reptiles called pterodactyls. Pterodactyls had long wingspans and large beaks. Scientists think pterodactyls used their beaks and claws to catch fish just like eagles.

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