You are going to create a decision tree to enable you to classify animals based on various features such as whether they have feathers or produce milk for their young.

1. Use your workbook to draw out your decision tree. It may be better to do this in pencil in case you make a mistake.
2. Open Session 5 data and click on the Animals tab. This shows different features for a range of animals. Your task is to produce a decision tree to separate out the different types of animal, e.g.  mammals, birds, fish.
3. To make this task easier sort the table on type (Data > Sort > Type).
4. To start your decision tree look at mammals – Can you find a feature that mammals have and no other type of animal has? This will be the first node on your decision tree.
5. Next, have a look a look at another type – can you spot a feature that only that type has? (It might help to hide the rows containing mammals – highlight these rows and click on Format > Hide/Unhide).
6. Continue analysing the data until you have split out all the different types of animal – for some decisions you may need a combination of features to split out two types.