Welcome to How Do We Classify Living Things? In this lesson, you'll learn how scientists sort every living thing into three big groups. We'll explore ideas that will help you see how animals, plants, and fungi are all different from each other. This will teach you some important ideas about how living things get food, move, and grow.
As we learn these ideas, you'll meet some new words! The words are underlined like this. You can hover over or tap any underlined word to see what it means in a little pop-up box. Let's get started!
Look around outside and you will see many living things! Some of them are animalsLiving things that move on their own and eat other living things for food.. An animal can run, fly, or swim to find its food. Animals cannot make their own food the way some other living things can — they have to go find it and eat it.
Other living things are plantsLiving things that make their own food using sunlight.. A plant cannot walk around, but it can grow very tall! Plants use sunlightLight from the sun that plants use to make their own food. to make their own food right where they are standing. That is why you often see plants growing toward a sunny window.
A third group of living things is called fungiLiving things, like mushrooms, that soak up food from other things instead of making it or eating it. — like mushrooms! A mushroomThe part of some fungi that pops up above the ground. does not make its own food like a plant, and it does not run around like an animal. Instead, it soaks up food from dead leaves and wood on the ground.
What comes next? After you read this, you'll practice all these vocabulary words with flip cards. Then comes the fun part — you'll explore the tree of life and see how animals, plants, and fungi are all related! Ready? Let's learn how to classify living things!
Welcome to How Do We Classify Living Things? In this lesson, you'll discover why animals, plants, and fungi get their energy in such different ways. The activities and interactive tools will help you understand these key differences and learn to classify living things like a scientist.
These big ideas come with important vocabulary words — science terms that help us describe what we observe. Throughout this passage, you'll see words that are underlined like this. You can hover over or tap any underlined word to see its definition pop up. After reading, you'll practice these words with flip cards and explore the interactive tree of life.
Every living thing needs energyThe power a living thing needs to move, grow, and survive. to survive, but different groups get their energy in different ways. Scientists sort living things into three main groups based on how they get that energy: animals, plants, and fungi.
Animals are consumersOrganisms that eat other living things for energy. — they get their energy by eating other living things. A deer eats grass, and a fox eats the deer. Animals live in nearly every habitatThe place where a living thing naturally lives. on Earth, from oceans to deserts, and most animals can move around to find their food.
Plants are producersOrganisms that make their own food, usually through photosynthesis. — they make their own food instead of eating other living things. Through a process called photosynthesisThe process plants use to turn sunlight, water, and air into food., plants use sunlight, water, and carbon dioxideA gas that plants take in from the air to make food. from the air to make their own sugar. As a bonus, this process also releases oxygenA gas in the air that plants release and animals breathe in. into the air for animals to breathe.
Fungi, like mushrooms and moldA fuzzy fungus that grows on old food and other damp surfaces., are decomposersOrganisms that break down dead material to absorb nutrients.. Instead of eating whole food like animals or making their own food like plants, fungi break down dead plants and animals and soak up the nutrientsSomething a living thing needs to grow and stay healthy. left behind. Even tiny yeastA tiny, single-celled fungus used to make bread rise., used to bake bread, is a decomposer at its core.
Ready to explore? Next, you'll practice these vocabulary words with interactive flip cards. Then you'll dive into the tree of life to see how these three groups are related through their shared organismAny individual living thing. ancestors. Let's discover why some living things eat, some make food, and some decompose!
Welcome to How Do We Classify Living Things? This lesson challenges you to classify organisms using scientific evidenceFacts or observations used to support a scientific claim. rather than surface appearance. Through the interactive tree of life and classification activities, you'll examine the cellular and reproductive traitsA characteristic or feature of a living thing. that separate the animal, plant, and fungi kingdoms — and discover why some organisms defy easy assumptions.
Understanding these classification systems requires precise scientific vocabulary. Throughout this passage, you'll see words that are underlined like this. You can hover over or tap any underlined word to reveal its definition. After reading, you'll reinforce these terms with flip card practice, then engage with the tree of life to see how these kingdoms are connected.
ClassificationThe way scientists sort living things into groups based on shared traits. is more than sorting by appearance — it means grouping organisms by shared, testable characteristics. Every organism belongs to a kingdomA major group in scientific classification, such as Animalia, Plantae, or Fungi., and every speciesA specific type of living thing, like a red fox or a sunflower. within it shares certain defining cellular features with its relatives.
Animals are multicellularMade of many cells, as opposed to just one. organisms that lack a rigid cell wallA rigid outer layer around some cells that gives them shape and support., which is part of why most animals can move freely. Nearly all animals reproduce through some form of reproductionThe process by which living things create new organisms like themselves. involving specialized cells, and their bodies are built to actively hunt, graze, or scavenge for energy.
Plants have cell walls made of celluloseThe tough material that makes up plant cell walls., a tough fiber that gives plant cells their rigid structure. Plants capture light energy using chlorophyllThe green pigment in plants that captures sunlight for photosynthesis., the green pigment that powers photosynthesis. Most plants reproduce using seeds, though some rely on spores instead.
Fungi also have cell walls — but theirs are built from chitinThe tough material that makes up fungal cell walls, also found in insect exoskeletons. instead of cellulose, the very same material found in insect exoskeletons. Below ground, most fungi grow as a hidden thread-like network called myceliumThe thread-like network that makes up the main body of most fungi, usually hidden underground., absorbing nutrients directly through their cell walls rather than eating or photosynthesizing. This is exactly why fungi cannot be lumped in with plants just because neither one walks or runs — their cells are built from fundamentally different materials.
Your investigation begins now. First, master the vocabulary through interactive flip cards. Then explore the tree of life, where you'll discover the idea of a common ancestorAn organism that two different groups both descended from. — the shared organism that two branches of life both descended from. As you work, consider: if an organism cannot photosynthesize, does that automatically make it an animal? The tree of life holds the answer.
Middle School & Up
Welcome to How Do We Classify Living Things? This lesson pushes classification beyond the animal, plant, and fungi kingdoms into the deepest level of biological organization: the domainThe highest rank in biological classification, above kingdom.. Through the interactive tree of life, you'll investigate how molecular evidence reorganized entire kingdoms and discover why fungi are genetically closer to animals than to plants.
Understanding this system requires precise scientific vocabulary. Throughout this passage, you'll see words that are underlined like this. You can hover over or tap any underlined word to reveal its definition. After reading, reinforce these terms with flip card practice, then use the tree of life to trace each domain down to its kingdoms.
All cellular life on Earth is categorized using a domain, which sits above the traditional kingdom rank. Under the widely accepted Three-Domain System, life is split into three broad domains, each defined by fundamental differences in cell structure and genetics rather than outward appearance.
EukaryaThe domain containing organisms with complex cells that have a nucleus, including animals, plants, and fungi. contains organisms with complex cells that have a nucleus — this is where animals, plants, and fungi belong, alongside a diverse group of mostly single-celled organisms called protists. Every eukaryoteAn organism whose cells have a nucleus enclosed by a membrane. you have ever seen, from a mushroom to a whale, falls under this single domain.
BacteriaA domain of microscopic, single-celled organisms that lack a cell nucleus. is a domain of microscopic, single-celled organisms that lack a cell nucleus entirely. ArchaeaA domain of microscopic organisms similar to bacteria but with distinct genetic traits, often living in extreme environments. looks superficially similar to bacteria under a microscope, but possesses completely distinct genetic and biochemical traits, often thriving in extreme environments like hydrothermal vents and salt flats where almost nothing else survives.
Within Eukarya, molecular phylogeneticsThe study of evolutionary relationships using DNA and other molecular evidence. has overturned a long-standing assumption: fungi were once classified alongside plants simply because neither group moves. Comparing the chitin-glucan complexThe combination of chitin and glucan that makes up a fungal cell wall. of fungal cell walls against plant cellulose, and analyzing shared genetic sequences, revealed that fungi and animals descend from a more recent common ancestorAn organism that two different groups both descended from. called OpisthokontaThe shared ancestral group that includes both animals and fungi. than fungi and plants do.
Your investigation begins now. First, master the vocabulary through interactive flip cards. Then explore the tree of life, tracing each taxonomyThe science of naming and classifying living things. level from domain down to kingdom. As you work, consider: if classification can be overturned by new evidence, what does that reveal about the nature of scientific knowledge itself?
Vocabulary Progression: Each grade band's vocabulary builds on the previous one. K–1 introduces the three kingdoms with concrete traits. 2–3 adds energy-role terminology (producer, consumer, decomposer). 4–5 incorporates cell-level structure and classification concepts. MS+ introduces formal taxonomy, molecular evidence, and the idea that classification itself evolves. Cards include auto-read functionality — K–1 and 2–3 cards read both term and definition aloud for early readers, while 4–5 and MS+ read only the term.
Standards Alignment: Specific state standards (Georgia GSE, Common Core, NGSS, and standards for North Carolina, New York, Michigan, and New Jersey) are detailed in the Standards Alignment section below.
Click any card to hear the word and see its definition.
15 terms • Focus: the three groups, basic traits, and simple needs
A living thing that moves on its own and eats other living things for food.
A living thing that makes its own food from sunlight and cannot walk or run.
A living thing, like a mushroom or mold, that gets food by soaking it up from other things.
The part of some fungi that pops up above the ground.
The flat green part of a plant that catches sunlight.
The part of a plant that grows underground and drinks up water.
To go from one place to another.
To get bigger over time.
Light from the sun that plants use to make food.
A small part that can grow into a new plant.
A tiny speck that some fungi use instead of seeds to make new fungi.
Able to grow, need food and water, and eventually die, like plants, animals, and fungi.
What a living thing needs to eat or make to get energy.
A liquid every living thing needs to survive.
A set of things that share something in common, like all animals or all plants.
15 terms • Focus: producers, consumers, decomposers, and how each group gets energy
An organism, like a plant, that makes its own food.
An organism, like an animal, that eats other living things for energy.
An organism, like a fungus, that breaks down dead plants and animals to get nutrients.
The process plants use to turn sunlight, water, and air into food.
Something a living thing needs to grow and stay healthy.
A fuzzy fungus that grows on old food and other damp surfaces.
A tiny, single-celled fungus used to make bread rise.
The part of a plant that holds it up and carries water to the leaves.
The stages a living thing goes through from birth to death.
The place where a living thing naturally lives.
A gas in the air that plants release and animals breathe in.
A gas that plants take in from the air to make food.
The power a living thing needs to move, grow, and survive.
Any individual living thing.
Everything around a living thing, including air, water, soil, and other organisms.
15 terms • Focus: cell structure, reproduction, and scientific classification
An organism that makes its own food, usually through photosynthesis.
An organism that gets energy by consuming other organisms.
A rigid outer layer around some cells that gives them shape and support.
The tough material that makes up plant cell walls.
The tough material that makes up fungal cell walls, also found in insect exoskeletons.
The way scientists sort living things into groups based on shared traits.
A major group in scientific classification, such as Animalia, Plantae, or Fungi.
A specific type of living thing, like a red fox or a sunflower.
The green pigment in plants that captures sunlight for photosynthesis.
The thread-like network that makes up the main body of most fungi, usually hidden underground.
Made of many cells, as opposed to just one.
The process by which living things create new organisms like themselves.
Facts or observations used to support a scientific claim.
A characteristic or feature of a living thing.
An organism that two different groups both descended from.
15 terms • Focus: kingdoms, domains, molecular evidence, and how classification changes
The highest rank in biological classification, above kingdom, such as Eukaryota.
A major classification rank below kingdom, grouping organisms with a shared body plan.
The shared ancestral group that includes both animals and fungi.
The ancestral group that includes plants, red algae, and glaucophytes.
The science of naming and classifying living things.
The study of evolutionary relationships using DNA and other molecular evidence.
An organism that feeds on dead or decaying organic matter.
A symbiotic partnership between fungi and plant roots that exchanges nutrients.
When unrelated organisms independently evolve similar traits.
Describing a group that includes an ancestor and all of its descendants.
An organism whose cells have a nucleus enclosed by a membrane.
The combination of chitin and glucan that makes up a fungal cell wall.
Moving an organism into a different scientific group after new evidence is found.
The distinction between organisms that make their own food and those that consume others.
Across 11 rounds, students sort organisms from honeybees to slime mold into the correct kingdom. The reasoning adjusts by grade band: K–1 sorts by observable traits, 2–3 reasons about how each organism gets its energy, 4–5 works from cell-level evidence, and MS+ takes on molecular and evolutionary reasoning with a follow-up question after each correct sort. Each round ends with a downloadable results receipt showing accuracy and standards alignment, so it works as a quick formative check or an independent station.
Questions and teacher notes adjust to your selected grade band above.
Fungi — mushrooms don't make their own food like plants do.
Bring a real mushroom or photo. Ask what parts look plant-like versus what's missing (no green leaves, no flowers).
Plants don't move on their own and often have leaves, stems, or roots.
Use two contrasting photos side by side and ask students to point to clues before naming the group.
It makes its own food using sunlight, water, and air, right where it is standing.
Students often assume every living thing has to go get food. Ask what the tree has that a squirrel does not (leaves that catch sunlight).
The squirrel grows, needs food and water, and moves on its own. The rock does none of those things.
Push for more than one clue. If students only say "it moves," ask about a sleeping animal or a plant to complicate it.
Decomposer — mold breaks down the bread to absorb nutrients from it, rather than making or eating whole food.
Connect to the classroom compost or a photo of a moldy fruit to make the decomposer role concrete.
The sunflower makes its own food using sunlight, so it is a producer. The rabbit cannot do that, so it eats plants to get energy, which makes it a consumer.
Listen for students who say the rabbit "makes" its food. Then push further: ask where the energy in the rabbit's food came from before the rabbit ate it.
Yeast is a fungus, and it is a decomposer. It breaks down sugars to get energy, which is what makes the dough rise.
Useful for separating "where we find it" from "what group it belongs to." Being handy to humans does not change its kingdom.
The animals would run out of food. Plants are the producers, so the consumers that eat them, and the consumers that eat those animals, would all lose their energy source.
Let students trace the chain out loud rather than confirming it. Ask where the energy in the meadow originally came from.
Fungus — both plants and fungi have cell walls, but only plants have chlorophyll for photosynthesis. Without it, the organism can't make its own food.
Push students to cite two traits, not just one, to justify their classification.
It means both kingdoms descended from the same organism far back in time, even though they look very different today.
Revisit the tree of life diagram and point to the branch point representing the shared ancestor.
Cell wall material (cellulose in plants, chitin in fungi) reflects how the organism is built at a cellular level, which tracks how closely related they are. Staying still is something unrelated organisms can both end up doing.
This is the core reasoning move of the lesson. If students pick the cell walls, ask what makes that evidence harder to arrive at by coincidence. If they pick immobility, ask them to name an organism that breaks the pattern.
No. Kingdom is decided by traits like cell wall material and how the organism gets food, not by how many cells it has. Both absorb nutrients and both have chitin cell walls, so both are fungi.
A productive trap: students often treat multicellular versus unicellular as a kingdom-level divide. Redirect them to the criteria they used earlier.
Cell wall chemistry (chitin vs. cellulose) and nutrition mode (absorptive vs. photosynthetic) showed fungi are chemically closer to animals in some respects. Classification updates when new evidence contradicts old groupings.
Use this as a springboard into "science is a process, not a fixed list of facts" — classification schemes change as tools and evidence improve.
Animals. Molecular phylogenetics places fungi and animals together in Opisthokonta, sharing a more recent common ancestor than fungi and plants do. Cell wall chemistry supports this: chitin rather than cellulose. Habitat and immobility turn out to be poor guides to ancestry.
The setup is written to pull students toward "plants," which is the productive wrong answer. Ask which kind of evidence they would trust over appearance and habitat, and why that evidence is harder to arrive at by coincidence.
You would need cellular and molecular evidence: whether its cells have walls, how it obtains energy, and its genetic relationships. Anemones are animals that capture prey. Appearance reflects the environment an organism lives in, not its ancestry.
Pairs directly with the companion game, which includes organisms chosen to defeat appearance-based sorting. Expect some students to answer "plant" from the description alone, which is the useful part. Ask what would have to be true of its cells for that to hold up.
Domain-level criteria are genetic and biochemical rather than visual. The differences in their genetic sequences and cell chemistry are deep enough to outweigh a shared appearance, which means visual similarity carries little weight at that rank.
Good bridge to why molecular tools reshaped taxonomy. Ask what classification would look like if only microscopes had ever been available.