Lab 1b Scientific Method and Measurements

The scientific method

Introduction

• A researcher starting a new line of research, begins by reviewing all the information they can acquire about the topic they will be studying.  What comes next, forming an hypothesis or making a prediction?

• A researcher who has tested their hypothesis, found that the test was failed (their new data do not conform to the prediction).  What do they do next, scrap/revise the hypothesis, or formulate another test of the same hypothesis?
• A researcher wants to know whether a new medication cures covid, so they give it to 100 people with covid in their clinic.  Which would be a useful control experiment for this study, to give a fake medication to another 100 patients with covid, or to give the real medication to 100 patients without covid?

Safety Precautions

• Inform your teacher immediately of any broken glassware, as it could cause injuries.
• Clean up any spilled fluids to prevent other people from slipping.
• Wash your hands with soap and water after completion of the activity.
• Do not touch the flat surface of the hot plate when it is on, or grab glassware with hot liquids unprotected- it will burn you!   Be careful not to spill hot liquids.

Materials

• Water
• Salt
• 250 ml Beakers
• Ice
• Hot plate
• Thermometer

For this activity, you will work in pairs.

Procedure

Step 1: Hypothesize:  We will hypothesize the affects of water temperature on the speed at which table salt dissolves in the water.  Given that the dissolving of salt requires interaction between the salt crystals and the water, and that warm water has more internal movement of molecules than does cool water, hypothesize whether salt will dissolve faster or slower when water temperature increases.  This is your hypothesis, record it in your lab notebook.

Step 2:  Predict and Test:  How could you test your hypothesis with the materials at hand in the lab?  What do you predict would be the result of your test, based on your hypothesis?   Write the test and prediction in your lab manual. 

Step 3:  Devise a Control Experiment:   How could you perform this same test in a parallel way that matches your first test, but does not alter the temperature of the water?

Step 4: Critical Analysis: Does the data from your test support your hypothesis? Why or why not?  Does the data from your control support this conclusion, and why or why not?  What methods could you use the improve on the testing method you used (or expand it to more solutes than mere table salt).  Write your test’s conclusion in your notebook, and your suggested improvements.

Step 5: Design and carry out another experiment:   Think of another question you could answer about the speed of salt dissolving in water, using the materials in the lab.  Formulate an hypothesis, make a prediction and design a test of that prediction, collect your data, and draw conclusions.   Describe all of these in your lab manual.

Discussion

1. Why do you think scientists have bothered to define the steps of the scientific method?
2. You observe that plants sitting in one location in your house grow faster than plants sitting in another location. Create a testable hypothesis to test why this occurs. Then, describe an experiment that would test your hypothesis that includes controls.