Distance detective: how far away can animals read a sign?
A playground mystery for a class: print the sign, put it on a wall and step back until you can only just read it. Measure that distance, then work out where a dog, a cat or an eagle would have to stand to read the same sign.
1. Print the sign
Z N H K
O C R S
D V Z O
2. Where would each animal have to stand?
You read the sign from 10 m.
| Animal | Stands at |
|---|---|
| Rhesus macaque | about 8.1 m |
| Harris's hawk | about 6.9 m |
| Horse | about 3.2 m |
| Rock pigeon | about 2.2 m |
| Tawny owl | about 1.5 m |
| Cat | about 1.4 m |
| Dog | about 1.3 m |
| Great horned owl | about 1.1 m |
| Chicken | about 1.1 m |
| European starling | about 99 cm |
| Cow | about 78 cm |
| House sparrow | about 77 cm |
| Brown rat | about 24 cm |
| House mouse | about 7.8 cm |
| Western honey bee | about 3.9 cm |
| Fruit fly (Drosophila melanogaster) | about 2 cm |
3. Record your class results
| Detective | My distance | Dog | Cat | My pick |
|---|---|---|---|---|
A simulation made from published eye studies. Not what the animal feels.
How does Distance detective work?
Sharper eyes can read the same sign from further away. Each animal's distance is your distance times how much fine detail its eyes pick up compared with yours, so pupils can check the table with a calculator.
Why do some animals have to stand so close?
Their eyes pick up less fine detail than yours. A sign you can read from 10 m, a dog has to get to about 1.3 m to see as clearly.
What do we need?
A printed sign, some tape, a tape measure or a trundle wheel, and a pencil for the record sheet. It works indoors in a long corridor too.