Scientific Method

Scientific method A series of steps that scientists follow to solve a problem Can go in any order Some steps can be skipped

Identify the Problem Problem you’re going to investigate Usually stated in the form of a question Real life example: how does brand of marker affect the distance the color travels?

Real life example of a lab A scientist wants to find out why sea water freezes at a lower temperature than fresh water The scientist goes to the library & reads lots of articles about the physical properties of solutions. The scientist also reads about the composition of sea water The scientist travels to a nearby beach & observes the conditions there. He/She notes the taste of the sea water and other factors such as waves, wind, air pressure, temperature, and humidty After considering all of this information, the scientist sits at a desk and writes “If sea water has salt in it, then it will freeze at a lower temperature than fresh water.” The scientist goes back to the lab and Fills 2 beakers with 1 liter of fresh water each Dissolves 35grams of table salt into one of the beakers Places both beakers in a freezer at -1°C Leaves the beakers in the freezer for 24hrs After 24hrs, the scientist examines both beakers and finds the fresh water to be frozen. The salt water is still liquid. The scientist writes in a notebook, “It appears that salt water freezes at a lower temperature than fresh water does.” The scientist continues, “I suggest that the reason sea water freezes at a lower temperature is that sea water contains dissolved salts, while fresh water does not.”

Make Observations Use your 5 senses Take data/notes on information Do some research Observations from real life example: The scientist traveled to the beach & used his 5 senses After 24hrs, he/she looked at the beakers

Make a Hypothesis Educated guess Form of a sentence “If…., then…” Hypothesis from real life example: When scientist wrote “If sea water has salt in it, then it will freeze at a lower temp. than fresh water.”

Test the Hypothesis/Experiment Test your hypothesis Procedures Repeated trials—when you re-do the experiment over & over again to see if you get the same results Experiment from real life example: In the lab he… Filled 2 beakers with 1liter of water Dissolved 35g of salt in one beaker Placed both beakers in freezer (at -1°C) Left the beakers in freezer for 24hrs

Variables from real life experiment: Constant/controlled variable —things that stay the same Responding/Dependent variable —results; what you’re looking for Manipulated/independent variables —the ONE thing that changes Variables from real life experiment: Controlled—freezer temp, amount of water, Manipulated—one had salt & the other didn’t Responding—temperature at which water freezes

Collect Data Take notes of what’s happening/results Usually in the form of a data table Data from real life example: Went to beach, wrote down conditions (wind, waves, temp, humidity, etc…) Also include experiment info Examined beakers in freezers after 24hrs

Study Data Look at data & compare it Usually in form of a graph or data table Analysis from real life example: Comparing your measurements Create a graph

Draw Conclusions Learn if your hypothesis was right or wrong Summary of your lab In paragraph form (complete sentences) Conclusion from real life example: State what happened—”it appears that salt water…” & “I suggest that the reason…” Tell if your hypothesis was right or wrong? What evidence/data do you have to support your ideas?