Year 4 Science: What a classification key is
Part of the Year 4 Science classification keys chapter. Chapter overview · whole chapter on one page
What a classification key is
A classification key is a set of questions that helps you to identify (name) a living thing. Each question asks about one feature that you can see, count or check. Each question has two answers: yes or no.
You start at the first question and follow the answer. Each answer sends you to the next question, or to a name. The key always ends with a name.
Key ideas
- A classification key asks yes or no questions about features.
- Each question has two answers: yes or no.
- You start at the first question and follow the answers, step by step.
- The key ends with the name of the living thing.
Method. Check the question for two answers.
- Read the question. The question asks whether the animal has feathers.feathers
- Check the answers. The answer can only be yes or no, so it is a yes or no question.yes or no
- Write the answer. yes
Check. Every question in a key has two answers, yes or no. ✓
Method. Look for the question with a yes or no answer that you can check.
- Look at a). Pretty is an opinion, so it is not a good key question.opinion
- Look at b). You can count the legs, and the answer is yes or no.count the legs
- Write the answer. b
Check. Only checkable features make good key questions. ✓
Method. Think about what a key is for.
- Think about the purpose. A key helps you to name a living thing, so you have identified it.name
- Choose the word. Naming a living thing is called identifying it.identified
- Write the answer. identified
Check. The key led you to the name, so the living thing is identified. ✓
Watch out
Watch out: a key only works if you answer each question carefully, using a feature you can see. A question about how a creature makes you feel is not a good key question.
Try it at home or school (with a grown-up). Look at a leaf from a tree in the garden, with a grown-up. Think of one yes or no question about it, such as: Is the leaf smooth on the edge? Answer it yes or no. Do not pick leaves from trees that you do not know.
Exam tip
Grown-up tip. Ask: “Can you answer that with yes or no? Can you see it, or check it?” Let your child say the word identify, and what it means.
Exercise 3A What a classification key is
Method. Read the start of section 3.1.
- Read the key idea. Each question has two answers: yes or no.yes or no
- Write the answer. yes and no
Check. Yes and no are the only two answers. ✓
Method. Read the definition in section 3.1.
- Read the definition. A key helps you to identify a living thing, by naming it.identify
- Write the answer. identify
Check. Identify means to say what something is. ✓
Method. Think about yes and no.
- Count the answers. The two answers are yes and no.yes and no
- Write the number. So each step has two answers.2
- Write the answer. 2
Check. Each question splits the living things into two groups. ✓
Method. Read the key idea in section 3.1.
- Read the key idea. The key always ends with the name of the living thing.name
- Write the answer. name
Check. The end of the key gives the name. ✓
Method. Check the answers to the question.
- Check the answers. The answer to this question is yes or no.yes or no
- Write the answer. yes
Check. A feature you can check makes a good key question. ✓
Method. Check whether there are two answers.
- Check the answers. The answer is a colour, such as green or brown, not yes or no.colour
- Write the answer. no
Check. A key question needs a yes or no answer. ✓
Method. Look for the question you can check.
- Look at a). Pretty is an opinion, so the answer changes from person to person.opinion
- Look at b). You can count the legs, so the answer is yes or no.count
- Write the answer. b
Check. Count the legs to check the answer. ✓
Method. Think about what a key can name.
- Think about the keys. Keys can be used for plants, such as leaves, as well as for animals.plants
- Decide. So Ali is not right.no
- Write the answer. no
Check. Section 3.3 uses a key for leaves. ✓
Method. Read the key idea in section 3.1.
- Think about plants. A key can name living things, which includes plants.living things
- Write the answer. true
Check. Plants are living things, so keys can name them. ✓
Method. Think about what you can see on a living thing.
- Think about the features. Legs, wings, leaves and fur can all be seen.can be seen
- Write one. Any one of these is a feature for a key question.one feature
- Write the answer. Accept any feature that can be seen or counted, such as legs, wings, leaves or fur.
Check. A feature you can check makes a good key question. ✓
Method. Think about a key as a set of steps.
- Think about the answers. A wrong answer at one step leads to the wrong name.wrong answer
- Write the next step. Checking the features again is the sensible next step.check again
- Write the answer. Accept any sensible answer, such as: check each question again, or check the features on the living thing.
Check. Checking again helps us find a mistake. ✓
Method. Put the ideas together.
- Describe the questions. The questions are yes or no questions about features.yes or no
- Describe the end. The key leads to the name of the living thing.the name
- Write the answer. Accept any sentence that says a classification key is a set of yes or no questions that leads to the name of a living thing.
Check. A key is a path of questions, ending in a name. ✓