A pictograph (or pictogram) uses icons to show how big each value is. In Year 2 every icon was worth one — six 🍎 meant six apples. In Year 4 the chart needs to show much bigger numbers, so each icon is worth more than one. The number is written in a small box at the bottom called the key.
Reading the key
The key tells you the value of one icon.
🍎 = 10
Now every full icon in the chart counts for 10. A row with five icons stands for 5 × 10 = 50.
A pictograph can use any key the designer chose: 2, 5, 10, 50 or even 100. Always read the key first.
Half-icons
When the value isn't a whole multiple of the key, the chart shows half an icon (or sometimes a quarter).
Key: 🍎 = 10. Row: 🍎 🍎 🍎 ½
Full icons: 3 × 10 = 30. Half icon: ½ × 10 = 5. Row total: 35.
Key: ⭐ = 50. Row: ⭐ ⭐ ½
Full stars: 2 × 50 = 100. Half: ½ × 50 = 25. Row total: 125.
Some charts also use a quarter or three-quarters of an icon. The same idea applies — multiply the fraction of the icon by the key.
A worked example
Number of trees planted in five years:
Key: 🌳 = 5
| Year | Icons | Trees |
|---|---|---|
| 2020 | 🌳🌳🌳 | 15 |
| 2021 | 🌳🌳🌳🌳 ½ | 22 |
| 2022 | 🌳🌳🌳🌳🌳🌳 | 30 |
| 2023 | 🌳🌳🌳 ½ | 17 |
| 2024 | 🌳🌳🌳🌳🌳 ½ | 27 |
Now answer:
Q. How many trees were planted in 2022?
6 × 5 = 30 trees.
Q. How many more trees in 2024 than in 2023?
27 − 17 = 10 trees.
Q. In which year was the number of new trees exactly twice the number in 2020?
2020 had 15. Twice that is 30. That's 2022.