FLAG - Classroom Assessment Techniques (CATs)

ConcepTests    (Screen 3 of 6)

Learning Goals
  • Communicate verbally using SMET terminology
  • Apply ideas and concepts
  • Integrate concepts
  • Work collaboratively with others


Instructor Goals


Suggestions for Use

Introduction of ConcepTests:
ConcepTests can be used in virtually any kind of SMET course, from introductory courses for majors or nonmajors through upper level courses. If possible, instructors should start to introduce ConcepTests the first day of class and may wish to mention the use of this and/or other collaborative learning methods in their syllabus. Students are sometimes resistant to change and may resent the introduction of a new format later in the course. If ConcepTests are used throughout the course, this format will seem natural to the class and the instructor. While many classes embrace the method upon its first use, it is not uncommon for an instructor and class to need to work through several ConcepTests before both are comfortable with the method and the class learns that they are expected to participate.

Presentation:
It is straightforward to build ConcepTests into the planning of a lecture. They can be presented to the class verbally and/or with the questions and possible answers written on a blackboard or overhead transparency. Pre-prepared ConcepTests can also be presented using overhead transparencies or electronic PowerPoint presentations. The number of ConcepTests used during any one lecture can vary substantially. In a typical 50-minute lecture, instructors have used anywhere from one to about half-a-dozen ConcepTests.

Demonstrations, designed to pique student interest and connect explanations with observable scientific phenomena, are traditionally presented with an introduction telling students what they will observe. A ConcepTest requiring students to predict the outcome is a convenient way to engage students and involve them in the demonstration. After discussion, the instructor does the demonstration and the students can determine whether or not their predictions were correct. ConcepTests can also be constructed around computer-based animations or film clips.

ConcepTests may incorporate graphs or tables of data. These ConcepTests assess not only students' conceptual understanding, but also their ability to extract information.

Student response:

Markings on card used for responding to ConcepTest.
Student responses to a ConcepTest can be evaluated in a number of ways: a raising of hands, a displaying of signs, a pushing of electronic touchpads, etc. Although a show of hands is the easiest and least expensive method, students may feel more comfortable and less conspicuous raising a sign whose orientation, color, and/or markings identifies their answer, as shown below. A similar method used in small classes has been to have students place a number of fingers on their chest which corresponds to the number of their chosen answer. Instructors may obtain a more accurate vote with the sign and finger methods since it is more difficult for a student to see how his or her classmates have voted. However, instructors should report the results of the vote to the class, so that students know the outcome. Instructors have the option of making voting mandatory or voluntary. In the latter case, signs and fingers mean all students vote at the same time, helping to identify students who have not yet voted.

Use of hands to respond to ConcepTest.

Some lecture rooms are equipped with touchpads. This technology makes it relatively easy to obtain statistical information on how students voted and how their votes were affected by discussion.

Grading:
Although ConcepTests are typically not themselves graded, instructors have found that a helpful element for the successful use of ConcepTests is an absolute grade scale, in which they guarantee at the very start of a course that a given level of course performance ensures a particular final grade (e.g., 85% and up guarantees an "A"; 70% a "B," etc.). This grading policy encourages students to help one another without fear of jeopardizing their grade, and it also enables students to track their progress in real time. The grade boundaries can always be lowered if exam scores are lower than anticipated, but the contract with the class is that they cannot be raised.

ConcepTests promote a classroom culture of cooperative learning that can make SMET courses more user-friendly. Their use can, for example, lead to more effective student participation in study groups. Many instructors have seen substantially enhanced student performance as a result of using ConcepTests with other cooperative learning methods. 2


Examples
ConcepTests are easily incorporated into lectures. An introduction to acids would be part of any introduction to chemistry. A traditional lecture or two might include the following ConcepTests, or the instructor might choose a selection from a menu of the following ConcepTests (correct answers are bold-faced):

  • introduce the autoionization of water to make protons and hydroxide ions
    Question: Consider the reaction for the autoionization of water, H2O H+ + OH-. Would a beaker of water contain more protons or more hydroxide ions?
    Answers: protons, hydroxide ions, equal amounts of both

    Question: Which is the correct Lewis dot structure for the hydroxide ion?
    Answers:

  • characterize the autoionization reaction as requiring heat
    Question: What happens to the amount of dissociation when a beaker of water is heated?
    Answers: more, less, same amount

    Question:The autoionization constant of water at body temperature is 2.8 x 10-14. The concentration of protons in pure water at body temperature is 1.7 x 10-7. Is the concentration of hydroxide ions the same, greater, or less than the concentration of protons?
    Answers:same, greater, or less

  • develop the concept of the pH scale as -log[H+], where [H+] represents the concentration of protons in units of molarity, M.
    Question: If [H+] = 10-3 M, what is the pH?
    Answers: -3, 3, 7
    Demonstration: The pH of 100 milliliters of a solution of the strong acid HCl is measured with a digital pH meter and shown to be about 1.

    Question: Roughly how many milliliters of water need to be added to reach a pH of about 2?
    Answers: 10, 100, 1000
    Demonstration (continued): Monitor the pH with each of these quantities of water added in turn.

  • demonstrate that the pH of neutral water is about 7; present a 10-1 M solution of the strong acid HCl and demonstrate that its pH is about 1, i.e., the value that would be calculated from its concentration
    Question: When the leads of a light bulb are immersed in pure water, will the light bulb light up?
    Answers: Yes, no

    Question: When the leads of a light bulb are immersed in 0.1 M HCl, will the light bulb light up?
    Answers: Yes, no

  • write the reaction for dissociation of HCl as HCl H+ + Cl-; sketch beakers with different relative concentrations of HCl, H+ and Cl- and ask which is the best representation of the distribution of species present in the 0.1 M HCl solution
    Question: Which of the following "molecular pictures" best represents a solution of HCl?
    Answers:     A.
    B.

    References
    2. Hake, R.R. American Journal of Physics, 1998, 66(1), 64-74.

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