A cat is a living thing! Living things (also called organisms) share five characteristics: (1) they need food, water, and air, (2) they grow and change, (3) they can reproduce (make babies), (4) they respond to their environment, and (5) they have cells. Rocks, toys, and water are non-living – they do not need food or water and they do not grow!

A teddy bear is non-living! Even though it looks like a bear, it is just a stuffed toy. It does not need food, water, or air. It does not grow or make baby teddy bears. Understanding the difference between living and non-living helps scientists study our world. Living things are called "biotic" and non-living things are called "abiotic."

A squirrel needs air to live! All animals need oxygen from the air to turn food into energy. Fish get oxygen from water using gills, but they still need oxygen. Plants need carbon dioxide from the air to make food through photosynthesis. Even tiny bacteria need air! Air is essential for all life on Earth.

A sunflower needs water to live! Plants use water to carry nutrients from the soil to their leaves and to make food through photosynthesis. Animals need water for digestion, to remove waste, and to keep their bodies at the right temperature. All living things – from the smallest bug to the largest whale – need water. That is why scientists look for water on other planets – water means life might be possible!

A bean sprout is growing! Growth is one of the most important signs of life. Living things get bigger and more complex as they get older. Plants grow from seeds to seedlings to full plants. Animals grow from babies to adults. This growth takes energy from food and water. Non-living things never grow on their own – they only change if someone changes them.

A chicken can reproduce! Reproduction is the process of creating new living things of the same kind. Some animals give birth to live babies (like humans, dogs, and cats). Some animals lay eggs (like chickens, fish, and frogs). Plants make seeds that grow into new plants. This is how life continues from generation to generation. A toy cannot make new toys – that is one reason it is non-living!

You pull your hand away from a hot stove! That is a reflex – your body responds to danger without you even thinking about it. Living things respond to light, temperature, sound, touch, and other changes. Plants grow toward sunlight. Worms dig away from light. Flowers close at night. These responses help living things survive. A rock does not move when you touch it – it has no response!

A cotton t-shirt was once alive! Cotton comes from cotton plants. The plant grew, needed water and sunlight, and was alive. After it was harvested and made into fabric, the shirt is no longer alive. Other examples: paper comes from trees, wool sweaters come from sheep, and wooden furniture comes from trees. Even gasoline comes from ancient plants and animals that died millions of years ago!

Fire is NOT alive! Even though fire needs oxygen and can spread, it is just a chemical reaction called combustion. Fire does not have cells – all living things are made of cells. Fire cannot reproduce (make baby fires) – it can only spread if there is more fuel. Fire does not grow from the inside like a living thing; it just burns more material. So fire is non-living. That is an important science distinction!

There are 3 living things: the butterfly (an insect), the mushroom (a fungus – mushrooms are alive even though they are not plants or animals), and the oak tree (a plant). The bicycle, cloud, and television are non-living. You are getting very good at telling the difference! Remember: if it needs food/water/air, grows, responds, reproduces, and has cells – it is alive. Great job, scientist!