TOpic 7 trees
English National Curriculum:
Key Stage 1
Tooltip content
understand what algorithms are; how they are implemented as programs on digital devices; and that programs execute by following precise and unambiguous instrutions.
Key Stage 2
Tooltip content
design, write and debug programs that accomplish SPECIFIC goals.
learning objectives
Tooltip content
to understand and explain the features of trees (tree structures).
success criteria
  • I can recognise a tree structure in everyday life.
  • I can identify the features of a tree or tree structure.
top tips
  • A tree stores data and is made up of nodes. There are different names for nodes in different parts of the tree structure.
  • These trees are upside down, because their roots are at the top and leaves are at the bottom. Root nodes are also the only nodes that do not have a parent node.
  • A parent node is the connected node above the current node – one step closer to the root node. A leaf is a node without a child. Siblings are two nodes that share a parent.
Common misconceptions



Root Nodes

Parents Nodes

Leaf Nodes

Child Nodes

Trees store data and are made up of nodes. They are like upside down trees, because their roots are at the top and their leaves are at the bottom.

A node is a structure which may contain a value or condition or represent a separate data structure.

A root node is found at the top of a tree structure. It does not have a parent, but it may have a child or children.

A parent node is the node above another node.

A leaf node is a node without a child.

A child node is a mode below another node. Two nodes below the same node are called siblings.

A tree or a tree structure is a hierarchical data structure that organises data elements, called nodes, by connecting them with links, called branches. This structure is used to help store and display large amounts of information in an easy to read format. This is the structure the file explores on computer systems takes on, folders within folders.

The overall structure resembles a tree when flipped upside down, with the root at the top and the branches expanding underneath. This is the exact same way we would represent a family tree.

The nodes are given names to more easily identify their position when the tree is not visible. A root node is at the top of the tree with nothing above it. You may have heard the term root directory before, the very top of a file tree. Every node below the root that also contains branches beneath it is a parent node. Any node without branches below is a leaf node. A parent node has child nodes. Sibling nodes share the same parent.