Year 3 Science | Living, Non-Living, Once-Living and Life Cycles of Living Things
Aligned with the Australian Curriculum: AC9S3U01
Welcome, curious critters and fantastic educators! 🐸🌻
Have you ever looked at a butterfly and wondered what makes it alive? Why does it flutter and fly, while a rock just sits there doing… well, nothing? And what about fossils? They’re not alive anymore, but they used to be!
If you’ve asked questions like these, you’re thinking like a scientist — and this post is for you.
Let’s explore what makes something living, non-living, or once-living, and take a peek into the life cycles that all living things go through.
🔍 What Is a Living Thing?
All living things share seven key features. These features help us tell the difference between something that is alive, something that was once alive, and something that has never been alive at all. Here they are in no particular order:
Movement
Living things can move. Sometimes it’s easy to spot — like a kangaroo hopping — and sometimes it’s slower or more subtle, like a plant bending towards the sunlight.
Nutrition
All living things need food to get energy.
- Animals eat plants or other animals — just like we do!
- Plants make their own food from sunlight through photosynthesis.
Respiration
This is the process of turning food into energy. All living things do it — even plants! It might sound tricky, but just remember: respiration is how living things power their bodies.
Excretion
Living things must get rid of waste. It might seem gross (we see you, dung beetle!), but it’s a vital process that keeps organisms healthy — and often helps other life forms too.
Sensitivity (Response to Environment)
Living things can sense and respond to changes around them:
- Plants grow towards light or close their leaves when touched.
- Worms wriggle when they feel vibrations.
- Humans respond to temperature, light, sound… and even emotions!
Reproduction
Living things can make more of themselves. Whether it’s turtles laying eggs or plants making seeds, reproduction is essential to keeping life going.
Growth (and Life Cycles!)
All living things grow and change over time — this is called a life cycle. From baby animals to blooming flowers, every living thing has a journey of growth.
🤔 What About Non-Living and Once-Living Things?
Let’s test your science smarts! Think about each of these — are they living, non-living, or once-living?
- 🐸 A frog – Living! It moves, eats, grows, and can make more frogs.
- 🪨 A rock – Non-living. It doesn’t move on its own, eat, or reproduce.
- 🦴 A fossil – Once-living. It was part of something alive long ago, like a dinosaur!
- 🌳 A tree – Living. It makes food, grows, and responds to sunlight.
- 🪵 A log – Once-living. It was once a tree, but it’s no longer alive.
- 🤖 A toy robot – Non-living. It can move, but only when someone turns it on. It doesn’t grow, eat, or make baby robots!
🌱 Life Cycles in Action
Let’s take a closer look at how living things grow and change.
🐸 Frog Life Cycle
- Egg – Frogs begin life as jelly-like eggs in water.
- Tadpole – The eggs hatch into tadpoles that swim using tails.
- Froglet – Legs grow, tails shrink, and lungs start to work.
- Adult Frog – Now they can hop on land, breathe air, and reproduce!
This big change is called metamorphosis.
🌻 Sunflower Life Cycle
- Seed – It all starts with a tiny seed.
- Germination – Roots and shoots begin to grow.
- Seedling – Leaves appear and the plant grows taller.
- Adult Plant – It blooms into a sunflower, which makes new seeds!
Even though frogs and sunflowers live in very different environments, they both grow, change, and reproduce — because they are living things.
🧠 Quick Recap: How Can You Tell If Something Is Living?
Ask yourself (note: I’ve changed the order from above):
- Move — Can it move?
- Respiration — Does it use energy?
- Sensitivity — Does it respond to the world around it?
- Growth — Does it grow?
- Reproduce — Can it make more of itself?
- Excretion — Does it get rid of waste?
- Nutrition — Does it need food?
If the answer is yes to most of these — it’s alive!
🎒 For Teachers
This blog post supports Year 3 Science, particularly the content description AC9S3U01 from the Australian Curriculum, which focuses on how scientists group things as living, non-living, or once-living based on observable features.
You can use this resource:
- As pre-learning before a unit on life cycles or biological classification
- Alongside a nature walk, science incursion, or museum visit
- With the Critter Quest Education video as an engaging multimedia introduction
- As a formative check-in after a hands-on activity
🧪 Final Thoughts
Whether it crawls, swims, grows in soil, or even used to be alive — the world is full of clues to what makes something living. By learning to observe and ask questions, we can start seeing life in all its wonderful forms.
Keep questioning, keep exploring — and don’t forget to check out more resources and videos at Critter Quest Education!
W. A. Greenly. 