Key Stage 2 design and technology · Design

KS2 annotated sketches and exploded diagrams: a parent guide

In Key Stage 2, children learn that a design is only useful if other people can understand it. They sketch quick ideas and add notes, draw a cross-section to show the inside of an object, and draw an exploded diagram to show how the parts fit together. These drawings are working tools for thinking and sharing, so they matter far more than neatness.

Sketches and exploded diagrams, explained

The programme of study says that when designing and making, pupils should be taught to generate, develop, model and communicate their ideas through discussion, annotated sketches, cross-sectional and exploded diagrams, prototypes, pattern pieces and computer-aided design. That is a long list, and in this guide we look at the drawn forms and the discussion that goes with them. Prototypes, pattern pieces and computer-aided design are covered in the companion guide on modelling.

An annotated sketch is a quick, freehand drawing with notes around it. The word “annotated” matters: a label only names a part (“handle”), whereas an annotation explains it (“curved handle, so small hands can grip it”). Good annotations give sizes, materials, how a part works and why a choice was made. Children are encouraged to draw several quick ideas rather than one polished one, because the first idea is rarely the best, and a sketch is meant to be thought with.

A cross-sectional diagram shows what is inside an object as if it had been sliced through. Think of a cut apple, or a sandwich cut in half: you can see the layers and the hollow spaces. In a cross-section, the surfaces that have been cut are usually shaded or drawn with a heavier line, and the walls and gaps are shown at the correct thickness. Designers use it to show how thick the walls are, where glue goes or what sits where.

An exploded diagram shows how something is assembled. The parts are drawn separately, pulled apart a little along the lines they would move along when put together, often with dotted guide lines joining them up. Flat-pack furniture and toy instructions use them all the time. For children, drawing one makes them think about the order of assembly and whether the parts really fit. Some pupils try simple three-dimensional drawing too, but at this age a clear two-dimensional version is quite enough.

All of these drawings support the iterative process the curriculum describes. Children sketch, discuss with a partner, improve the design, make a model, test it and go back to the drawing. A clear drawing also lets someone else say whether the design will work before any materials are cut.

Words your child will hear

Sketch: A quick, rough drawing made to try out an idea.
Annotate: To add notes to a drawing that explain choices, sizes and how parts work.
Label: A word or short phrase that names a part of a drawing.
Cross-section: A drawing of an object as if it were cut through, to show what is inside.
Exploded diagram: A drawing with the parts spread out along the lines they fit together on.
Dimensions: The measurements of an object, such as height, width and thickness.
Assembly: Putting the separate parts together to make a whole product.

What the National Curriculum says

The programme of study for Key Stage 2 says:

When designing and making, pupils should be taught to generate, develop, model and communicate their ideas through discussion, annotated sketches, cross-sectional and exploded diagrams, prototypes, pattern pieces and computer-aided design
Through a variety of creative and practical activities, pupils should be taught the knowledge, understanding and skills needed to engage in an iterative process of designing and making.

Objectives from the National Curriculum in England, © Crown copyright, used under the Open Government Licence v3.0.

Try it: drawing a pencil pot three ways

A child has designed a pencil pot made from a cardboard tube 10 cm tall and 7 cm wide, a card disc that forms the base, and a decorated paper sleeve that slides over the tube. How can the design be shown with an annotated sketch, a cross-section and an exploded diagram?

Annotated sketch. Draw the outside in light pencil, then add notes that give sizes and reasons rather than just names.
```
Tube: 10 cm tall, 7 cm wide
Wide base so it won’t tip over
Sleeve: pattern chosen by users
```
Cross-section. Imagine slicing the pot down the middle and draw the cut face. Show the tube walls as two thick vertical lines, and the base as a thick line near the bottom, set 1 cm up inside the tube with its glue tabs folded up. Add a note: “glue tabs 1 cm”.
Exploded diagram. Draw the parts in a column, spaced apart, joined by dotted lines. Number them in the order they are put together (the tube first, then the base glued inside it, then the sleeve slid on) and label the material of each.
```
  Sleeve (3) paper
      :
      :
  Tube (1) card
      :
      :
  Base disc (2) card
```
Add dimensions to all three drawings, checking that the numbers match. The tube must be 7 cm wide in every drawing, and the disc must match the inside width of the tube, a little less than 7 cm, so that it fits snugly inside.
Check with a partner. Ask them to say how the pot is made from the drawings alone. If they get stuck, add a note or move a dotted line.

The pencil pot is shown by three linked drawings: an annotated sketch that explains the choices, a cross-section that shows how the base fits inside the tube, and an exploded diagram that shows the parts and the order of assembly.

Common mistakes and how to help

Thinking an annotation is just a label

Labelling is the first thing children learn to do on a diagram, and naming a part feels like finishing the job.

What helps: Ask “why?” or “how?” after each label. “Handle” becomes “handle, curved, so small hands can grip it”.

Believing a sketch must be neat and accurate

Children are used to art being judged on how it looks, so they rub out and start again or avoid drawing at all.

What helps: Explain that a sketch is for thinking. Set a time limit of a few minutes to draw several ideas and keep them all, even messy ones.

Scattering the parts of an exploded diagram anywhere on the page

“Exploded” sounds like a mess, so children spread parts out at random.

What helps: Show a flat-pack instruction sheet. The parts are lined up along the lines they fit together on, kept the same way up, and numbered in order.

Confusing a cross-section with a side view

Both show an object from the side, so they look similar to begin with.

What helps: A side view shows the outside. A cross-section shows the cut surface, so you can see inside. Cut an apple in half to prove the difference.

How to help at home

Cut it and draw it. An adult cuts a piece of fruit or a sandwich in half. Your child draws the cut face and labels the layers or parts. That is a cross-section.
Explode a sandwich. Draw a sandwich with the bread, filling and spread pulled apart along dotted lines. Number the order in which you would put it together.
Annotate an everyday object. Pick a cup, a torch or a school bag and sketch it quickly. Add three annotations that explain why a feature is useful, not just what it is called.
Read the instructions. Next time you put together something from a flat pack or a toy kit, look at the diagram with your child. Ask what the dotted lines and arrows mean.
Explain a drawing to someone. Ask your child to talk you through their design drawing as if you had to make it. If you are confused, a note or a measurement is probably missing.

Builds on

Key Stage 1: Design criteria and users
Key Stage 1: Drawings, templates and mock-ups

Leads on to

Key Stage 3: Understanding user needs
Key Stage 3: Identifying design problems
Key Stage 3: Writing a design specification
Key Stage 3: Biomimicry and user-centred design
Key Stage 3: Communicating design ideas