Classification Keys

Despite the fact that 99.9% of all living organisms, that ever existed, are now extinct there is still a large variety on Earth today.

Hence it is important to be able to classify organisms in order to be able to find out their names. Also classification helps scientists to be able to understand the relationships between organisms and to investigate the theory of evolution.

Now we will try a simple sorting activity to organize some dogs into groups according to their similarities...

Keys

Divide the dogs into two groups

Group A Group B

We divide the dogs into groups by asking a question to which there is a yes or no answer...

Is the dog large (above 65cm)?

Large Dogs Small Dogs

We can now divide each group down into further sub divisions...

white and grey coats brown and black coats

What question could be used to divide the large dogs down into further groups?

Does the dog have a brown and black coat?

No Yes

Finally the groups can be divided down into individual dogs to which we can then give the names.

What question has been used to separate these two dogs?

Does the dog have curly hair?

Airedale Terrier Rotweiller

yes no

By asking questions that divide the dogs we can produce a key. To save space biologists list the questions and give instructions at the end as to which question to go to next.

1. Is the dog over 65cm tall?

If yes go to question 2

If no go to question 5

2. Does the dog have a brown and black coat?If yes go to question 3

If no go to question 4

3. Does the dog have a wooly coat?

Yes… Airedale Terrier

No…Rotweiller

1. Is the dog over 65cm tall?

If yes go to question 2

If no go to question 5

2. Does the dog have a

brown and black coat?

If yes go to question 3

If no go to question 4

3. Does the dog have a wooly coat?

Yes… Airedale Terrier

No…Rotweiller

Copy down the key and then complete it to classify the rest of the large dogs.

Hint: you will write question 4

Question: What will question 5 be about?

Answer> The small dogs.

Activity

Example Answer

Does the tail curl upwards?

Question 4

Yes No

Akita Old English sheepdog

Activity

Now complete the key, starting with question 5, for the small dogs. You can make your own questions up.

Does the dog have a snub nose?

Yes No

Question 5

Go to question 6 Go to question 7

Example Answer

Does the dog have long hair?

Question 6

Yes No

Pekinese Bulldog

Question 7

Does the dog have very long ears?

Yes No

Basset hound Dachsund

Extension/Homework:

Collect worksheet 1 – 4Complete for homework

Using Keys