Look at these Irish wildlife cards: a robin, a frog, an oak, a hedgehog. How would you sort them into groups so someone else could find each one again?

A branching key is a path of yes-or-no questions that ends on a name. Every question splits what is left into two.

Here is one for four things that are not alive at all: a bicycle, a bus, a boat and an aeroplane.

Question 1: does it have wheels that touch the ground?
No: the boat and the aeroplane... except an aeroplane does have wheels on the ground. So that question is not clean enough, and a key only works if every answer is certain.

Better question 1: does it travel on water?
Yes: the boat.
No: the bicycle, the bus, the aeroplane.

Question 2: does it have an engine?
No: the bicycle.
Yes: the bus and the aeroplane.

Question 3: does it fly? And now every one has its own end.

Your wildlife cards are next, and the questions are yours to choose.

In your group, sort the Irish wildlife photo cards with yes-or-no questions about features. Write each question on a sticky note and stick the cards under Yes or No until every living thing has its own named place. Then record your finished branching key on your Investigation Journal page: list each question in order and write which living thing sits at each end point.

On the board you will see the same eight Irish wildlife cards you sorted on paper. We will answer one clear yes-or-no feature question at a time and send each living thing to its own end point, until every card sits on its own. Watch where each card goes and say if you agree or if you would have answered differently.

A mystery Irish wildlife photo is on the board. It is not one of the eight cards you sorted. We will follow a shared class branching key of yes-or-no feature questions. Answer from what you can see, not from guessing a name. On your Investigation Journal page, record each feature decision and the name you reach at the end.