The Spectrum of Assessments

     One of my favourite units to teach is the one on chemical bonding. In chemistry, bonding is where all of the action is. As teachers, we usually begin by labelling chemical bonds as ionic, polar covalent, or non-polar covalent. We explain that the classification of these three types of bonds is based on the differences between the electronegativity values of the atoms involved in the bond. We then point to a neat little chart showing the cut-off points for each category, pass out a periodic table showing each element's electronegativity value, and have students determine whether the bonds in various compounds are ionic, polar covalent, or non-polar covalent.

http://phs.psdr3.org/science/chemistry1/Smith/BondingReview.htm

Unfortunately, the classification of bonds as ionic, polar covalent, or non-polar covalent is somewhat arbitrary - in fact many chemistry textbooks cite different electronegativity difference cut-off values for each category. In reality, there are not three categories of bonding, there is a spectrum of bonding.

http://www.bbc.co.uk/scotland/learning/bitesize/higher/chemistry/energy/bsp_rev1.shtm

Therefore, it is more appropriate to describe a bond a more polar than another, or less ionic than another based on where it falls in the bonding spectrum.

     As educators, we tend to try to classify types of assessments in much the same way, labelling them as either objective assessments or subjective assessments. This is becoming more and more difficult as the variety of assessment strategies increases. Watch the following video to see some of the many creative assessment strategies available today.

http://www.youtube.com/watch?v=PszymHlse20

 

It is becoming increasingly obvious that classroom assessment rarely fits neatly into predefined categories. For example, traditionally objective assessment strategies such as multiple choice questions, can also be said to have a subjective component due to cultural and geographic bias in the questions themselves. Likewise, subjective assessments such as open-ended inquiry labs often have several objective components such as the right and wrong answers to calculations. It is therefore, more appropriate to also describe assessment in terms of a spectrum, with different assessments having greater or lesser objective/subjective components.

http://www.carla.umn.edu/assessment/vac/evaluation/p_2.html