Year 4 Science: Making a key
Part of the Year 4 Science classification keys chapter. Chapter overview · whole chapter on one page
Making a key
To make a key, write one question at a time. Each question must have a yes or no answer, and it must split the living things into two groups. Then ask a new question about one of the groups, until each group has one name.
Put the questions in a sensible order. Start with a question that splits the living things into the biggest clear groups, such as: Does it have a backbone?
Key ideas
- Each key question has a yes or no answer.
- Each question splits the living things into two groups.
- Choose a feature that you can see or check.
- Put the questions in a set order, and check each one.
Method. Think about which question splits the animals into the biggest clear groups.
- Think about the backbone. The backbone question splits vertebrates from invertebrates, which is a large clear split.large clear split
- Choose the first question. So the backbone question should come first.Does it have a backbone?
- Write the answer. Does it have a backbone?
Check. A shell is only found on some invertebrates, so it is a later question. ✓
Method. Think about a yes or no question.
- Think about the answers. Each answer sends the living things into one of two groups.two groups
- Write the number. So one yes or no question makes two groups.2
- Write the answer. 2
Check. Yes and no make two groups. ✓
Method. Look for the question that splits the two animals.
- Look at a). Pretty is an opinion, and both animals may be pretty.opinion
- Look at b). A robin has feathers, and a goldfish does not, so it splits them.splits them
- Write the answer. b
Check. Feathers are a clear feature that splits the two animals. ✓
Watch out
Watch out: a key question must have a clear answer. “Is it big?” is a poor question, because two people may disagree about what big means.
Try it at home or school (with a grown-up). Choose four objects from the house or garden that are living things, with a grown-up, such as a plant and a bird picture. Write one yes or no question that separates two of them. Ask a friend to answer it.
Exam tip
Grown-up tip. Ask: “Does your question have a yes or no answer? Does it split the group into two?” Let your child change a poor question into a clear one.
Exercise 3D Making a key
Method. Check the answers.
- Check the answers. The answer to “Is it a plant?” is yes or no.yes or no
- Write the answer. yes
Check. A key question must have a yes or no answer. ✓
Method. Look for the question with a clear answer.
- Look at a). Pretty is an opinion.opinion
- Look at b). The robin has feathers and the goldfish does not.feathers
- Write the answer. b
Check. Feathers split the two animals clearly. ✓
Method. Think about the two answers.
- Think about the answers. The yes answers form one group, and the no answers form the other.two groups
- Write the number. So the question makes two groups.2
- Write the answer. 2
Check. Yes and no give two groups. ✓
Method. Think about the biggest split.
- Think about the split. The backbone question divides vertebrates from invertebrates.divides
- Write the question. So it is a sensible first question.first question
- Write the answer. Does it have a backbone?
Check. The key in section 3.2 starts with this question. ✓
Method. Think about a feature that one animal has and the other does not.
- Think about the features. A dog has fur, and a frog does not.fur
- Write the question. Does it have fur or hair? separates them.fur or hair
- Write the answer. Accept any yes or no question that separates a frog from a dog, such as: Does it have fur or hair?
Check. Test your question on both animals to check it. ✓
Method. Think about a feature each one has.
- Think about the features. A robin has feathers, and a goldfish has fins.feathers and fins
- Write the question. Either feature makes a clear yes or no question.yes or no
- Write the answer. Accept any yes or no question that separates them, such as: Does it have feathers? or Does it have fins?
Check. Each question gives a different answer for the two animals. ✓
Method. Read the key idea in section 3.4.
- Read the key idea. Each key question has a yes or no answer.yes or no
- Write the answer. no
Check. Yes and no are the two answers. ✓
Method. Read the question and the answer.
- Read the answer. The answer is yes, so the key gives the name for animals with 6 legs.yes
- Write the name. Animals with 6 legs are insects, so a ladybird is an insect.insect
- Write the answer. insect
Check. A ladybird has 6 legs and 3 body parts. ✓
Method. Think about the answer.
- Think about big. Big means different things to different people.different things
- Write the reason. So two people could answer the question in different ways.different ways
- Write the answer. Accept any reason that says big is not clear, so two people could answer it differently.
Check. A key question needs an answer that everyone can check. ✓
Method. Think about what you can check.
- Think about what you see. Legs, wings, leaves and fur can be checked by looking.checked by looking
- Write one feature. Any one of these works as a key question.one feature
- Write the answer. Accept any feature that can be checked by looking, such as legs, wings, leaves or fur.
Check. Good key features can be checked. ✓
Method. Think about animals without a backbone.
- Think about the group. Animals without a backbone are invertebrates, such as spiders and snails.invertebrates
- Write the question. A question about legs or a shell can separate these animals.legs or shell
- Write the answer. Accept any question about an animal without a backbone, such as: Does it have 8 legs?
Check. The next question only needs to split the invertebrates. ✓
Method. Think about the steps.
- Think about the answers. Each answer decides which question to ask next.decides
- Write the reason. So if the order changes, the key gives a different name.different name
- Write the answer. Accept any sentence that says each answer decides which question comes next, so the order must be followed.
Check. Following the order gives the correct name. ✓