Applied Science - Science and Math (4B)
Lab 

   
OBJECTIVES:
  • Comparing qualitative and quantitative data.
  • Analyzing and interpreting data.
VOCABULARY:
  • experiment
  • mathematics
  • observation
  • qualitative
  • quantitative
MATERIALS:

Students will experiment with vinegar and baking soda.

BACKGROUND:


In this lab, students discover that many times there are qualitative and quantitative components to science experiments.  Qualitative data describes the situation and reaction in descriptive terms.  For example, qualitative involves the senses including sight, taste, hearing, touch, and smell.  This would include color and shape.  Quantitative includes those things that can be measured.  For example, describing something as a square would be qualtitative, but measuring it and stating that it is 2 cm. by 2 cm. is quantitative. 

In this experiment, students will be collecting both quantitative and qualitative data.  They will be performing a chemical reaction caused by the mixing of vinegar and baking soda.  Baking soda plus vinegar reacts to form carbon dioxide (the bubbles) and a liquid residue.  The more baking soda students start with, the more vinegar they will need to complete the reaction. Even if more vinegar is added, a reaction will continue if there is more carbon dioxide to be released from the baking soda (sodium bicarbonate).  (This experiment uses a lot of vinegar!)  

When students record what happens during  this reaction, they should be aware that they must be able to describe the reaction.  They should be thinking:  What do I see, hear, or smell?  This is qualitative science.  However, when they plot the data and interpret the result, it is quantitative science.  Students will make a bar graph of their results.

PROCEDURE:

  1.  Prepare baking soda and vinegar in containers so that they can be easily distributed when ready.   If there are time constraints this lab can be done in two periods.  Students may do the hands-on portion one day and interpret the results on a subsequent day.
      
  2. Discuss the difference between qualitative and quantitative data.  Tell students that today they will be doing an experiment in which they need to record both qualitative and quantitative information
      
  3. Pass out the lab sheets.  Review the lab procedure with the students.  Remind them that they are not only recording quantities of vinegar and baking soda used (quantitative), but are also describing the reaction (qualitative).   As they are performing the lab they should be asking themselves: What do I see, hear, or smell?
      
  4. When the students have finished the lab, collect all the vinegar and baking soda.  (If you leave these out on the tables the students will keep experimenting until they have to go home!)  Explain how you would like them to do the bar graph.  Remind them that each bar should be a different color to make it easier to read.
      
  5. Review the conclusion questions with the students.  Encourage the students to realize which part of the experiment was quantitative and which part was qualitative.   

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