Making a Simple Dichotomous Key

This fun activity for KS1 children to make a dichotomous key for their friends to use is an interesting way to introduce the concept of classification of living things. It can also be extended for KS2 by applying these principles to real living things found in an outdoor environment using more advanced observation and identification skills.

Resources

• Mini beast counters / dolly mixtures/ dinosaur toys
• Rulers
• Hand lenses/ magnifying glasses
• Paper and pencils
• Plant identification guides/ keys (optional)
• Animal families cards (optional)

This activity can be introduced with a discussion on the reasons why we give objects (or plants and animals) names.

Dichotomous Keys and Classification

Dichotomous keys are used to help people to determine the identity of items in the natural world including plants and animals. They are made up of a series of questions with two possible answers that lead the user to the correct identification.

Did you know: the word Dichotomous means ‘divided into two paths’. Classifications are devised by people to help them to identify living things but these classifications can change as new species are constantly being discovered.

We used bug counters for the children to sort according to their different characteristics but you could use any group of objects with simple similarities and differences including toy dinosaurs, or dolly mixture sweets. Practising grouping (both living and non living things) will help children to understand how we classify living things and give them names and is also a good opportunity to discuss the characteristics of living things.

Step 1 Observe and describe the similarities of the objects
Step 2 Make a simple table to record the characteristics of each of the objects
Step 2 Group the objects according to their characteristics
Step 4 Using a piece of paper they should draw a key or tree diagram with a series of yes or no questions be used to classify each of the insects.
Step 5 Once they have created their key, they can then check each of the pathways by sorting the objects.
Step 6 Children can then share their keys for others to try using to identify and name the different objects.

Extension Activities

This activity provides a good opportunity for children to begin to make simple observations of living things and start to use appropriate volcabulary to describe the features observed. For a more advanced activity children can create and use keys for a range of different living things found in their local environment or beyond.

Making observations

Give children a selection of real leaves, flowers or seeds to draw or create a rubbing using crayons and observe (using a hand lense or magnifying glass) and describe their different features including colour, texture, shape, size, number of petals/ veins. These observations can be recorded in a table. The leaves can then be grouped, sorted and classified using a dichotomous key.

Identifying animals

Children can also use animal families cards to classify cards by sorting and creating tree diagrams. They should first spend 20 minutes in groups sorting the cards into different groups and discussing the reasons for sorting into each group. This will allow children to learn about the key features of animal groups including vertebrates, invertebrates, reptiles, mammals, insects, amphibians and fish.

Using Keys for Identification of Plants

Children can use a key such as Plants UK to classify plants that they have found or observed on a nature walk. The different plants observed can be recorded by taking photographs.

Useful Resources

Science and Plants for Schools
Forestry Commission Online Tree ID Key
Opal Explore Nature Bugs Count App
Woodland Trust’s Ladybird ID key

This Activity Could Cover the Following Learning Outcomes:

English National Curriculum 2014 Science

KS1 Working scientifically – identifying and classifying

Year 1

• Plants – Identify and name a variety of common wild and garden plants including deciduous and evergreen trees.
• Animals including humans – identify and name a variety of common animals including fish, amphibians, reptiles, birds and mammals
• Identifying differences, similarities or changes related to simple scientific ideas and processes

Year 2

• Living things and their habitats – explore and compare the differences between things that are living, dead, and things that have never been alive

Year 3

• Animals including humans – Identify that humans and some other animals have skeletons and muscles for support, protection and movement.

Year 4

• Living Things and their habitats – recognise that living things can be grouped in a variety of ways, explore and use classification keys to help group, identify and name a variety of living things in their local and wider environment.

Year 6

• Living things and their habitats – Describe how living things are classified into broad groups according to common observable characteristics and based on similarities and differences, including micro-organisms, plants and animals. Give reasons for classifying plants and animals based on specific characteristics.

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