Introduc on to Science
What is science? You have likely taken several classes throughout your career as a student, and know that it is more than just chapters in a book. Science is a process. It uses evidence to understand the history of the natural world and how it works. Scien fic knowledge is constantly evolving as we understand more about the natural world. Science begins with observa ons that can be measured in some way, and o en concludes with observa ons from analyzed data.
Following the scien fic method helps to minimize bias when tes ng a theory. It helps scien sts collect and organize informa on in a useful way so that pa erns and data can be analyzed in a meaningful way. As a sci‐ en st, you should use the scien fic method as you conduct the experiments throughout this manual.
Concepts to explore: The Scien fic Method
Scien fic Nota on
Data Collec on
Scien fic Reasoning
Wri ng a Lab Report
Figure 1: The process of the scien fic method
Lab 1: Introduc on to Science
The process of the scien fic method begins with an observa on. For ex‐ ample, suppose you observe a plant growing towards a window. This ob‐ serva on could be the first step in designing an experiment. Remember that observa ons are used to begin the scien fic method, but they may also be used to help analyze data.
Observa ons can be quan ta ve (measurable), or qualita ve (immeasurable; observa onal). Quan ta ve observa ons allow us to rec‐ ord findings as data, and leave li le room for subjec ve error. Qualita ve observa ons cannot be measured. They rely on sensory percep ons. The nature of these observa ons makes them more subjec ve and suscep ble to human error.
Let’s review this with an example. Suppose you have a handful of pennies. You can make quan ta ve observa‐ ons that there are 15 pennies, and each is 1.9 cm in diameter. Both the quan ty, and the diameter, can be pre‐
cisely measured. You can also make qualita ve observa ons that they are brown, shiny, or smooth. The color and texture are not numerically measured, and may vary based on the individual’s percep on or background.
Quan ta ve observa ons are generally preferred in science because they involve “hard” data. Because of this, many sci‐ en fic instruments, such as microscopes and scales, have been developed to alleviate the need for qualita ve observa‐ ons. Rather than observing that an object is large, we can
now iden fy specific mass, shapes, structures, etc.
There are s ll many situa ons, as you will encounter throughout this lab manual, in which qualita ve observa‐ ons provide useful data. No cing the color change of a leaf or the change in smell of a compound, for example,
are important observa ons and can provide a great deal of prac cal informa on.
Once an observa on has been made, the next step is to develop a hypothesis. A hypothesis is a statement de‐ scribing what the scien st thinks will happen in the experiment. A hypothesis is a proposed explana on for an event based on observa on(s). A null hypothesis is a testable statement that if proven true, means the hypothe‐ sis was incorrect. Both a hypothesis and a null hypothesis statement must be testable, but only one can be true. Hypotheses are typically wri en in an if/then format. For example:
If plants are grown in soil with added nutrients, then they will grow faster than plants grown without added nutrients.
If plants grow quicker when nutrients are added, then the hypothesis is accepted and the null
hypothesis is rejected.
Figure 2: What affects plant growth?