Look at these five leaves from Irish hedges, lawns and school gardens. How would you tell a friend which one is which — without pointing?
Scientists use a special tool called a branching key. Today we will complete one as a class and use it to name a mystery leaf.
A branching key is a path of yes-or-no questions that leads to a name. A feature is something you can see that helps tell one thing apart from another.
Here is one for something easy: the things in a pencil case. A pencil, a rubber, a ruler and a scissors.
Question 1: is it longer than your hand?
Yes: the ruler.
No: the pencil, the rubber and the scissors.
Question 2, for the no group: does it have a point?
Yes: the pencil and the scissors.
No: the rubber.
Every question splits the pile in two. Every path ends on a name. That is all a key is.
Soon you will build one for our leaves. That one is yours.

In groups, look closely at five leaves: oak, holly, dandelion, daisy and fern. Use a hand magnifier. What features can you see?
On your Investigation Journal page, note one clear feature for each leaf — edge, shape, or how it is divided.
We will complete a yes-or-no branching key for our five leaves. Look at the interactive activity on the board.
The questions are:
For each leaf, answer the questions in order. The first yes tells you its feature box: prickly edges, many small leaflets, deep wavy lobes, or a jagged or toothed edge. A leaf that gets no every time goes in smooth plain edge. When every leaf is in a box, we say which leaf is which: holly, fern, oak, dandelion or daisy.
Your group gets a mystery leaf. Do not look at the name. Follow your branching key step by step — yes or no at each question — and decide which leaf it is.
Write your answer and one reason on your Investigation Journal page. Be ready to explain your path to the class.
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