Science starts with noticing. A scientist looks closely, listens, smells and feels (but never tastes anything in a lab), and writes down what she finds. Then she asks a question she could test.
Key idea
An observation is something you notice with your senses or a tool: "The puddle got smaller by noon." A hypothesis is a guess about why that you can test: "The sun dried the puddle."
Good questions can be tested. "Why are flowers pretty?" is hard to test. "Do bean seeds sprout faster in a warm room or a cool room?" can be tested with seeds, two rooms and a calendar.
Worked example: Observation or guess?
Mia writes: "The ice cube on the plate melted in 20 minutes. I think the warm air melted it."
- "The ice cube melted in 20 minutes" is what she saw and timed: an observation.
- "I think the warm air melted it" is her idea about why: a hypothesis she could test.
Answer: The first sentence is an observation; the second is a hypothesis.
Common mistake
Writing a guess as if you saw it. "The dog was hungry" is a guess; "the dog ate all its food in one minute" is what you observed.
Try it at home
- Sit by a window or in the yard for five minutes with a notebook.
- Write five observations: colors, sounds, things that move, the sky.
- Pick one and write a question you could test, like "Do more birds come to the yard in the morning or the afternoon?"
Going further. The Handbook of Nature-Study is full of things to observe outdoors, and the Science Lab lets you test ideas on screen.