What is a poster and what makes it work?
A poster is a printed or digital sheet that shares one message with many people at a glance. A promotional poster invites people to something (an event, a product, an idea). Other kinds: public-information posters (health, safety), and posters for a school exhibition that explain a project.
A poster is seen from a distance, for a few seconds, by people who are busy. So it must be:
- Simple: one main message.
- Visible: big headline, strong contrast.
- Clear: the reader knows what, when, where and what to do.
Plan first: goal, audience and grid
Before drawing, write down:
- Goal: what should people do after seeing it? (Come to the fair, save water, buy a ticket.)
- Audience: children, parents, teachers, the whole town? This decides words, pictures and colours.
- Message: one sentence of up to 10 words.
- Size and place: A3 (297 × 420 mm) for a notice board, A2 or bigger for a hall, a phone screen for social media.
Then make 2–3 small thumbnail sketches with a simple grid: top zone for the headline, middle for the picture, bottom for details. Pick the best one.
Hierarchy: headline, image, details
Visual hierarchy means the most important thing is the biggest and boldest, so the eye reads in the right order.
- Headline: 2–5 words, bold, the largest text. A short slogan below can add feeling.
- Image (focal point): one big, simple picture or icon. Draw your own or use one you have permission to use. Placing it on a rule-of-thirds line makes the layout lively.
- Details: smaller text answering the 5 W's: what, who, when, where, why. Add a call to action ("Register by Friday", "Bring a bottle").
- Logo or contact: smallest, at the bottom.
Use white space (empty space) around blocks; a crowded poster is hard to read. Line things up along one edge or the centre (alignment). Use at most two font families.
Colour, contrast and readability
- Use 2–3 colours: one main colour, one accent, and black or white for text.
- Contrast = the difference between text and background. Dark blue on pale yellow or white on dark grey reads well; yellow on white does not.
- Colours carry feelings: blue and green feel calm and natural (water, health); red and orange feel urgent or exciting; use them to match your message.
- The 3-metre test: stick the poster on a wall and step back 3 m. Can you read the headline and understand the topic in 3 seconds? A simple rule: about 2.5 cm of letter height for every 3 m of distance.
Exhibition panels and brochures
For a school exhibition, posters work as a set: give them the same colours, fonts and layout so the stand looks like one project. Number them in the order visitors should read. Keep text short; put one key fact per panel and add a diagram or photo of your work.
A brochure is a small folded leaflet people take home. The common tri-fold is an A4 sheet folded into 3 panels (6 faces). Plan it: front cover = title + image (like a mini-poster); inside 3 panels = the main information in short sections with headings; back = contact, map sketch or summary. Same hierarchy rules apply, but the text can be smaller because it is read in the hand.
Try it: make your own poster
Pick a real event (a class fair, a cleanliness drive). On A4 paper, draw three thumbnail sketches in 10 minutes. Choose one, then make it on A3 with the H-I-D order and only 3 colours. Do the 3-metre test with a friend: ask them what, when and where after just 3 seconds. In the 3D, step 6 lets you test headline size and colours first.
Key formulas and definitions
- Hierarchy order: Headline → Image → Details → Logo
- 5 W's: what, who, when, where, why + call to action
- Colours: 2–3 (main + accent + text colour)
- Readability rule: about 2.5 cm letter height per 3 m distance
- A3 = 297 × 420 mm; A4 = 210 × 297 mm; tri-fold brochure = A4 in 3 panels
Worked examples
1. A poster will hang in a corridor where people read it from 6 m away. How tall should the headline letters be?
2.5 cm per 3 m → 6 m needs about 2 × 2.5 = 5 cm tall letters.
2. Improve this headline: "The Annual Interschool Science And Technology Exhibition 2026 Organised By Our School".
Too long for a headline. Use "SCIENCE FAIR 2026" as the headline and move "Interschool · organised by our school" into the small details.
3. A student made a poster with red text on a green background and 6 colours. What would you change?
Red on green has weak contrast and is hard for colour-blind readers. Reduce to 2–3 colours, for example dark green text on a pale background with one orange accent.
Common mistakes
- Too many words. If the poster needs a paragraph, it should be a brochure.
- Everything the same size. Without hierarchy, the eye does not know where to start.
- Pretty but weak colour pairs like yellow on white, or too many colours.
- Missing details: no date, time or place, so people cannot act on the message.