Animals & Nature · Unit 3

Animal Groups

Mammals, birds, reptiles, amphibians, fish and creatures without backbones

Grouping animals is how a bewildering variety becomes learnable, and the standard vertebrate classes are a good place to start because their defining features are things you can check.

The unit covers mammals, birds, reptiles, amphibians and fish, and then the invertebrates - which are not really a group at all, just everything left over once you remove the backbones.

This unit breaks down into 18 short steps and 108 questions, starting at difficulty 1 and building to 3. Below you can see exactly what it covers, how the path is structured, and worked examples with explanations.

Steps: 18
Questions: 108
Difficulty: 1-3

What this unit covers

Birds
Reptiles and Amphibians
Fish
Mammals
Animals Without Backbones

Where this fits

Follows What Is an Animal? Each class gets its own unit later.

Where people slip

Invertebrate is a convenience term, not a biological group. Insects, jellyfish and octopuses have far less in common with each other than any of them do with a fish.

How the unit is structured

Animal Groups runs as 18 short steps that unlock in order. 13 are practice rounds and 5 are challenge rounds that pull together everything before them. Questions start at difficulty 1 and climb to 3 as you progress.

Step 1 · easierStep 18 · harder

Challenge rounds

Example questions

30 real questions from this unit, with the answer and the reason behind it, grouped by what they practise. There are 108 in the unit altogether.

Animals Without Backbones

Choose all that applyLevel 1
1. Which of these are invertebrates? Pick all that apply.
- Earthwormcorrect
- Jellyfishcorrect
- Beetlecorrect
- Frog
Worms, jellyfish and beetles all lack backbones.
Odd one outLevel 1
2. Which of these is NOT an insect?
- Spidercorrect
- Ant
- Bee
- Beetle
A spider has eight legs, so it is an arachnid.
Build the sentenceLevel 2
3. Build a sentence about animal variety.
Answer: Most animal species have no backbone
Most animal species have no backbone.
Fact or fibLevel 2
4. Starfish belong to a group called echinoderms, with five-part symmetry.
Answer: True
True. Sea urchins and sea cucumbers are relatives.
Match the pairsLevel 2
5. Match each animal to its group.
Answer: Owl = Bird; Fox = Mammal; Lizard = Reptile; Salmon = Fish
Every animal fits into a group with shared features.
Multiple choiceLevel 2
6. Which invertebrate is famous for being remarkably intelligent?
- The octopuscorrect
- The barnacle
- The sponge
- The coral polyp
Octopuses solve puzzles, use tools and learn quickly.

Birds

Multiple choiceLevel 1
7. What covers a bird's body?
- Featherscorrect
- Fur
- Scales all over
- Smooth wet skin
Only birds have feathers.
Choose all that applyLevel 2
8. Which are true of all birds? Pick all that apply.
- They have featherscorrect
- They have beakscorrect
- They lay eggscorrect
- They all fly
Feathers, beaks and eggs are shared by every bird.
Fill the blankLevel 2
9. Birds and mammals are both ____-blooded animals.
- warmcorrect
- cold
- blue
- thin
Both keep a steady internal body temperature.
True or falseLevel 2
10. Flightless birds usually lack a prominent keel on the sternum.
Answer: True
True. Without powered flight, the huge muscle anchor is unnecessary.
Type the answerLevel 2
11. What hard part of a bird's face does it use to eat?
Answer: beak
A beak, also called a bill, replaces teeth in birds.
Choose all that applyLevel 3
12. Which adaptations support flight in birds? Pick all that apply.
- Pneumatic bonescorrect
- Large flight muscles on a keelcorrect
- One-way lung airflowcorrect
- Heavy solid teeth
Light skeletons, powerful chest muscles and efficient lungs all support flight.

Fish

Fill the blankLevel 1
13. A fish takes oxygen from the ____ using its gills.
- watercorrect
- air
- sand
- sun
Water flows over the gills and oxygen passes into the blood.
Multiple choiceLevel 1
14. Which of these is a fish?
- Sharkcorrect
- Dolphin
- Whale
- Seal
A shark is a fish, though its skeleton is made of cartilage.
True or falseLevel 1
15. Most fish are covered in scales.
Answer: True
True. Overlapping scales protect the body.
Type the answerLevel 2
16. What body part lets a fish take oxygen from water?
Answer: gills
Gills sit behind the head on each side.
Choose all that applyLevel 2
17. Which are true of fish? Pick all that apply.
- They live in watercorrect
- They use gillscorrect
- Most are ectothermiccorrect
- They all have lungs
They live in water, use gills and are ectothermic, with a few exceptions.
Choose all that applyLevel 3
18. Which are ray-finned fish? Pick all that apply.
- Salmoncorrect
- Codcorrect
- Seahorsecorrect
- Ray
Salmon, cod and seahorses are all ray-finned bony fish.

Mammals

Picture questionLevel 1
19. 🐄 Which animal group does this creature belong to?
- Mammalscorrect
- Birds
- Fish
- Reptiles
A cow has fur and feeds its calf milk, so it is a mammal.
True or falseLevel 1
20. Humans are mammals.
Answer: True
True. We have hair, feed our babies milk and are warm-blooded.
Choose all that applyLevel 2
21. Which are features of mammals? Pick all that apply.
- Hair or fur at some stagecorrect
- Milk-producing glandscorrect
- A steady internal temperaturecorrect
- Gills for breathing
Hair, milk glands, warm blood and a four-chambered heart are all mammal traits.
Fact or fibLevel 2
22. Whales and dolphins are fish.
Answer: False
False. They are mammals that breathe air and feed their young milk.
Multiple choiceLevel 2
23. What is a placental mammal?
- One whose young develop fully inside the mothercorrect
- One that lays eggs
- One that lives in water
- One with no fur
The young develop inside the mother, nourished through a placenta, until well formed.
Sort into groupsLevel 2
24. Sort each mammal into its group.
Answer: Platypus = Egg-laying; Kangaroo = Pouched; Koala = Pouched; Lion = Placental
Mammals divide into egg-layers, pouched mammals and placentals.

Reptiles and Amphibians

Sort into groupsLevel 1
25. Sort each animal as a reptile or an amphibian.
Answer: Snake = Reptile; Tortoise = Reptile; Frog = Amphibian; Newt = Amphibian
Reptiles have dry scales, amphibians have moist skin.
Choose all that applyLevel 2
26. Which are amphibians? Pick all that apply.
- Frogcorrect
- Toadcorrect
- Salamandercorrect
- Gecko
Frogs, toads, newts and salamanders are all amphibians.
Fact or fibLevel 2
27. Most amphibians need water to lay their eggs.
Answer: True
True. Their soft eggs would dry out on land.
Multiple choiceLevel 2
28. What covers a reptile's body?
- Dry scalescorrect
- Soft fur
- Feathers
- Wet slimy skin
Reptiles have dry scaly skin.
True or falseLevel 2
29. In many reptiles the sex of hatchlings depends on the temperature of the nest.
Answer: True
True. Temperature-dependent sex determination occurs in crocodilians and many turtles.
Type the answerLevel 3
30. What is the term for sex being determined by incubation temperature?
Answer: temperature-dependent sex determination
Temperature-dependent sex determination raises real concerns in a warming climate.

Where these questions come from. Each unit starts as a plan of the concepts it should cover and the difficulty it should span. Questions are written against that plan with AI assistance, then checked by a validator that rejects anything without a single defensible answer, an explanation, or plausible wrong options. How we write questions sets out the whole process, and corrections are fixed in the bank and reach the site and the app the same day.

How you practise

This unit mixes 11 different question formats, so you are recalling and applying rather than recognising the same layout every time.

Build the sentence
Choose all that apply
Fact or fib
Fill the blank
Match the pairs
Multiple choice
Odd one out
Picture question
Sort into groups
True or false
Type the answer

Practise Animal Groups

108 questions across 18 steps. Start with step one and crawl at your own pace.

Play this unit

More units in Animals & Nature

See all 18 units in Animals & Nature →