Prelabs: What's the Use

1
Pre-labs What's the Use?

• Anne Kondo, Wendy Elcesser
• and John Woolcock
• Department of Chemistry
• Indiana University of Pennsylvania

2
Overview

• Pre-lab assignment questions students answer
  after reading the experiment but prior to
  attending lab
• Why is this of interest?
• Why give pre-lab assignments?
• What IUP does with pre-labs
• Conclusions

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Why focus on pre-labs?

• CER Separates
• Formation of General Chemistry Teaching Circle
• Adoption of Working With Chemistry lab manual
  (Wink, Gislason, Kuehn)
• Review of everything we did in/for lab

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Purpose of Pre-lab

• Make sure students read/prepare for experiment
• ask for definitions
• ask about chemical concepts
• given practice calculations
• ask about safety concerns
• What are students learning?

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Sample Pre-lab CER TECH 488 Visible Absorption

• Define blank, absorption spectrum, analytical
  wavelength, standard solution, Beers Law plot
• Explain why we use the analytical wavelength
  use a blank wipe the outside of a cuvette
  dilute concentrated solutions
• Analyze a sample set of data (generate and use a
  Beers Law plot)

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Working With Chemistry Lab Program

• Experiments come in groups of three
• Skill-building lab
• Foundation lab scenario-based
• Application lab
• D. Wink, S. Gislason J. Kuehn, W.H. Freeman,
  2000

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Working With ChemistryLaboratory Program

• Absorption Spectroscopy
• Skill-building lab Spectrophotometry of Dyes
• Foundation lab Spectrophotometric Determination
  of Cu2
• Application Lab Total Serum Iron Assay
• Pre-labs in the manual are traditional
• IUP tailored pre-labs depending on lab type
• Grading weight of pre-labs 0 - 36

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Working With ChemistrySkill-building Pre-labs

• Educational purpose of Skill-building pre-lab
• focus on concepts
• connect lab to scenario

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Sample Skill-building Pre-labAbsorption
Spectroscopy

• Answer concept questions about complementary
  colors wavelengths
• Calculate absorbance from percent of light
  absorbed
• Use Beers law to predict effect of halving
  concentration (tied to scenario)

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Working With Chemistry Foundation Pre-labs

• Educational Purpose of Foundation Pre-labs
• recall scenario
• transfer of concepts from Skill-building lab
• help students begin to design procedures
• calculations are tied to procedure development

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Sample Foundation Pre-labAbsorption Spectroscopy

• Review scenario
• Calculate quantities for 10 mol NH31 mol Cu2
• Construct data table for l A data
• Calculate quantities for serial dilutions
• Construct data table for concentration A data
• Make connection to skill-building analytical
  wavelength effect of concentration

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Working With ChemistryApplication Pre-labs

• Educational purpose of Application Pre-lab
• transfer of concepts and techniques from
  Skill-building and Foundation labs
• design procedure
• do calculations tied to procedure development
• construct data tables
• explain what they will do

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Sample Application Pre-labAbsorption
Spectroscopy

• Calculate quantities for serial dilutions
• Calculate quantities for excess complexFe2
• Analyze absorption spectrum of
  Fe2-ferrozine complex
• Construct data tables
• Explain how they will determine Fe2unknown

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Over three weeks of pre-labs.

• We make conceptual and procedural connections
  from one week to next
• We tie all calculations to those needed to start
  a particular experiment
• We dont give sample data for calculation
  practice
• We leave safety to the pre-lab discussion

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Positive Aspects of Pre-labs

• Students have strong reasons to prepare for lab
• Answering pre-lab questions requires
  understanding of procedure
• Instructor has opportunity to identify conceptual
  problems before experiment begins
• Strong correlation between proper pre-lab
  preparation and good experimental design,
  efficiency in lab and good report writing

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Negative Aspects of Pre-labs

• Students who do not do the pre-lab are
  disadvantaged
• Students can get frustrated
• Pre-labs are time-consuming

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Conclusions

• Pre-labs can be used to make students think!
• A good pre-lab sets a student up for a positive
  learning experience in lab

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Acknowledgements

• National Science Foundation (CCLI AI)
• Donald Wink, Sharon Gislason Julie Kuehn
• IUP Reflective Practice Project and Center for
  Teaching Excellence
• IUP General Chemistry Teaching Circle

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References

• D. J. Wink, S.Fetzer Gislason, J.Ellefson Kuehn,
  Working With Chemistry A Laboratory Inquiry
  Program, W.H.Freeman, 2000.
• N.E. Griswold, M.L. Gillette, CER Separate TECH
  488, CER, 1997.
• J. Mazlo, D. Dormedy, J. N-Anderson, T. Urlacher,
  G. Carson, E. Hass, P. Kelter, J. Coll. Sci.
  Teach., XXXI, p318.
• M. Rollnick, S. Zwane, M. Staskun, S. Lotz, G.
  Green, Int. J. Sci. Ed., 23, 1053, 2001.
• W.S. Lyle, W.R. Robinson, J. Chem. Ed., 79, 663,
  2002.
• M.R. Abraham, M. Cracolice, A. Palmer Graves, A.
  Aldhamash, J Kihega, J. Palma Gil, V. Varughese,
  J. Chem. Ed., 74, 591, 1997.
• Http//www.iup.edu/teachingexcellence/services.