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Lesson 01 – Living Things

Read About Living Things


Read the vocabulary terms to understand the reading better.


Organisms are living things that can grow, use nutrients, and produce young.


Cells are the smallest structural units of a living organism that can function by themselves.


Respiring means to take in oxygen and give out carbon dioxide.


Unicellular means to have only one cell.


Multicellular means to have many cells.

Carbon Dioxide

Carbon dioxide is a clear, colourless, odourless gas that humans breathe out and plants take in.


A habitat is the natural environment in which a living organism lives.


Bacteria are microscopic living organisms that can be helpful and can sometimes cause illness.

Living Things

You know that our world is made up of living and non-living things.
A bird is a living thing. A rock is not. But what makes something alive? We are alive, but so is a tree. What do we have in common with a tree?

Characteristics of Living Things

Living things are called organisms. All organisms share certain characteristics:

  • Organisms are made up of one or more cells. Cells are the basic unit of life. They are the smallest unit of living matter. Some organisms, such as bacteria, have just one cell. They are unicellular. Other organisms, such as humans, have many cells. They are multicellular.
  • Organisms use materials and energy from their environment to grow and develop. Humans eat food. With the help of water, their bodies turn the food into energy. Green plants use sunlight and water to make their own food for energy.
  • Organisms respond to their environment. A cat might respond to a loud sound by running away. Flowers respond to sunlight by turning toward the Sun.
  • Organisms respire. This means they exchange gases with their environment. Animals and humans breathe in air (oxygen) and breathe out carbon dioxide. Plants do the opposite when they are making food. They take in carbon dioxide and release oxygen.
  • Organisms reproduce. They can produce copies of themselves. Bacteria reproduce by splitting in two. Some plants reproduce through seeds. Some animals lay eggs. Other animals give birth to live young.
Trees are an example of an organism
Some birds lay up to 17 eggs

To learn more about the characteristics of living things, watch the video by MooMooMath and Science on Youtube.


Needs of Living Things

To stay alive, organisms must meet their needs. These needs include food and water to get the energy they need to grow, develop, and reproduce. They need air to get the gases they need. They need the right place to live (habitat) that provides everything they need to stay alive.

Now Show What You Know!

Complete some questions about the reading selection by clicking “Begin Questions” below.