A scientist makes observations about something he or she wants to learn more about.
So They Can Have The Accurate Answers
A scientist may create an hypothesis on the basis of their observations. If their observations are carelessly made or recorded then any hypotheses they offer will be inaccurate reflections of nature. A scientist may alternatively collect observations to test an hypothesis. If these observations are carelessly made or recorded then the conclusions that the scientist makes about the hypothesis could very well be incorrect. At the very least the conclusions they draw would not be based on sound evidence (because the observations are unsound).
By making mistakes.(:
From observations or experiments
If the scientist based on what they already know can misinterpret their behaviors
Make a hypothesis
Because answers need to be based on real data in order to be accurate, not based on personal bias.
Before the scientific revolution scientists would do mostly observations. These observations are what lead to the rise of patterns and the need for the scientific revolution.
Lab tools can greatly improve the observations made by a scientist. This is due to the fact that the lab tools can quantify the changes the scientist is seeing, resulting in usable data.