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  Observation beyond our eyes
We typically think of observations as having been seen "with our own eyes," but in science, observations can take many forms. Of course, we can make observations directly by seeing, feeling, hearing, and smelling, but we can also extend and refine our basic senses with tools: thermometers, microscopes, telescopes, radar, radiation sensors, X-ray crystallography, mass spectroscopy, etc. And these tools do a better job of observing than we can! Further, humans cannot directly sense many of the phenomena that science investigates (no amount of staring at this computer screen will ever let you see the atoms that make it up or the UV radiation that it emits), and in such cases, we must rely on indirect observations facilitated by tools. Through these tools, we can make many more observations much more precisely than those our basic senses are equipped to handle.

Hubble space telescope microscope submersible
Tools like the Hubble Space Telescope, microscopes and submersibles help us to observe the natural world.

Observations yield what scientists call data. Whether the observation is an experimental result, radiation measurements taken from an orbiting satellite, an infrared recording of a volcanic eruption, or just noticing that a certain bird species always thumps the ground with its foot while foraging — they're all data. Scientists analyze and interpret data in order to figure out how those data inform their hypotheses and theories. Do they support one idea over others, help refute an idea, or suggest an entirely new explanation? Though data may seem complex and be represented by detailed graphs or complex statistical analyses, it's important to remember that, at the most basic level, they are simply observations.

Observations inspire, lend support to, and help refute scientific hypotheses and theories. However, theories and hypotheses (the fundamental structures of scientific knowledge) cannot be directly read off of nature. A falling ball (no matter how detailed our observations of it may be) does not directly tell us how gravity works, and collecting observations of all the different finch species of the Galapagos Islands does not directly tell us how their beaks evolved. Scientific knowledge is built as people come up with hypotheses and theories, repeatedly test them against observations of the natural world, and continue to refine those explanations based on new ideas and observations. Observation is essential to the process of science, but it is only half the picture.

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  • In science, observations are used as evidence to help us figure out which of our explanations are correct.


Correction: Scientists build knowledge through a complex process that involves coming up with ideas about how things work and then seeing if observations back those explanations up. Read more about it.

science in action
When the structure of DNA was unraveled, scientists had no microscopes powerful enough to look into the molecule. Instead they relied on indirect observation and X-ray crystallography. Learn the whole story behind this important discovery in The structure of DNA: Cooperation and competition.

key points
You can help students understand the differences between observation and inference (e.g., between observations and the hypothesis supported by them) by regularly asking students to analyze lecture material, text, or video. Students should try to figure out which aspects of the content were directly observed and which aspects were generated by scientists trying to figure out what their observations meant. For example, while watching a video on mammoth fossils, students could be asked to keep lists of scientists' direct observations and the inferences they made from them.

Hubble image provided by NASA; microscope photo from Scott Bauer/USDA; submersible photo from NOAA Ocean Explorer
