Comparison of Student Learning in Challenge-based and Traditional Instruction in Biomedical Engineering

Abstract

This paper presents the results of a study comparing student learning in an inquiry-based and a traditional course in biotransport. Collaborating learning scientists and biomedical engineers designed and implemented an inquiry-based method of instruction that followed learning principles presented in the National Research Council report “How People Learn” (HPL). In this study, the intervention group was taught a core biomedical engineering course in biotransport following the HPL method. The control group was taught by traditional didactic lecture methods. A primary objective of the study was to identify instructional methods that facilitate the early development of adaptive expertise (AE). AE requires a combination of two types of engineering skills: subject knowledge and the ability to think innovatively in new contexts. Therefore, student learning in biotransport was measured in two dimensions: A pre and posttest measured knowledge acquisition in the domain and development of innovative problem-solving abilities. HPL and traditional students’ test scores were compared. Results show that HPL and traditional students made equivalent knowledge gains, but that HPL students demonstrated significantly greater improvement in innovative thinking abilities. We discuss these results in terms of their implications for improving undergraduate engineering education.

Appendix A: Challenge Example

Challenge 6. The Danger of Hot Coffee Burns

Every year in the US there are thousands of accidents at restaurants in which hot beverages are spilled onto customers causing scald burns that are severe enough to require hospitalization. In the most extreme cases, death results. A small fraction of these accidents result in law suits against various parties involved in the food service industry, the most publicized being the infamous McDonald’s case in which a jury awarded an elderly New Mexico woman more than 2 million dollars in 1994. Part of the public outcry to this case was based on the concept that spilling a cup of coffee is such a trivial event that it could not be worth such a large legal settlement. Thus, the focus of this challenge is to answer the question “How dangerous is it to spill a cup of hot coffee into your lap?”

You may use the following information in your analysis. The Coffee Brewers Association recommends that coffee be held at a temperature of 185 °F for serving to customers, although a recent survey of the food service industry indicates the actual temperatures at fast food restaurants is somewhat lower. Many of the scald accidents occur while customers are seated in their vehicles at fast food drive-thru windows. A typical container contains 8 oz of liquid. The clothing worn by customers varies over a broad spectrum depending on geographic location and time of year, activity of the customer in conjunction with the visit to the drive-thru, and customer life style.

A consideration inherent to the issue of how dangerous is spilled coffee is how the level of danger can be modulated by altering the coffee temperature. For example, a recent scientific study demonstrated that the preferred drinking temperature of coffee is 140 °F. Thus, it is appropriate to ask how a progressive reduction in serving temperature would change the injury hazard associated with a spill.

Appendix B: Pre–Posttest

SECTION I. (10 min)

• 1. The flow of blood through microcirculatory blood vessels can have a large influence on heat transfer and temperature regulation in human tissues.

  • a. As the blood flows through the vasculature is the mechanism of heat exchange with the surrounding tissue most likely to be dominated by a process of

    • (i) Conduction

    • (ii) Convection

    • (iii) Radiation

  • b. Which vascular components will provide the most effective venue for heat exchange between blood flowing through them and the tissue in which they are embedded?

    • (i) Aorta

    • (ii) Arteries

    • (iii) Arterioles

  • c. Consider a comparison of the heat exchanges by the flowing blood and by the tissue in a very small volume of flesh. Is the magnitude of the heat exchange for the blood

    • (i) Smaller

    • (ii) The same

    • (iii) Larger

• 2. The alveoli of the lungs present a structure in which there is mass exchange between gas flow (air) and liquid flow (blood).

  • a. The fluid flow regimes of air and blood may be matched of different in the alveoli. Is the most likely combination

    • (i) Air: laminar and blood: turbulent

    • (ii) Air: laminar and blood: laminar

    • (iii) Air: turbulent and blood: laminar

    • (iv) Air: turbulent and blood: turbulent

  • b. During one complete respiratory cycle the air pressure in the alveoli when compared to the air pressure in the immediate environment is

    • (i) Always greater

    • (ii) The same

    • (iii) Always lesser

    • (iv) Fluctuates cyclically between being greater and lesser

  • c. During respiration the air flowing in the lungs at the center of a bronchial passageway has a velocity in comparison to air at the bronchial wall surface that is

    • (i) Always larger

    • (ii) Sometimes larger and sometimes smaller

    • (iii) Always smaller

    • (iv) Always the same

SECTION II. (15 min)

• 3. This is a very complex problem. A full solution would require extended attention and a number of iterations. However, one of the keys to success in extended problem solving is how you get started. Our goal is to access how you get started on a problem.

Your task in this problem is to begin designing the device described below.

In severe trauma patients hypothermia is a common occurrence and issues in a significant increase in mortality. This situation is particularly grave for wounded soldiers for whom it has been shown that mortality doubles when the body core temperature reaches a value of 34 °C or lower. Patients suffering from severe trauma tend to become hypothermic regardless of the environmental temperature, and in a war zone, such as the recent US involvement in Iraq and Afghanistan, casualties have suffered hypothermia at a rate in excess of 90%. Consequently, the prevention and treatment of hypothermia have been identified as being a major deficiency in American combat medical capability.

The Department of Defense is seeking solutions to solving the problem of preventing and treating hypothermia in war casualties. Owing to constraints imposed by the battlefield environment, there are a number of very specific limitations that must be enforced for any possible solution. Rapid evacuation to a Forward Surgical Hospital typically requires 5 h and a ride in a cold helicopter. To be effective a warming device must be able to transmit energy to the body core at a rate of 60 W over the 5-h period. It has been determined that the most effective method of delivering heat directly to the body core is via arteriovenous rewarming, being far more efficient than any surface warming technology. The device must be compact, light in weight, and robust (capable of being dropped from a helicopter at 150 feet onto a concrete surface). The device must contain its own power supply since there is generally not an external electrical service available on a battlefield and during critical phases of transport. Batteries are too heavy and are inefficient. Thus, the energy source of choice for heating is compressed butane, which can be used to fire a burner in a small heat exchanger through which a minor fraction of the patient’s blood flows. A surgical group has proposed designing a unit capable of warming 300 mL of blood per minute. The pumping source to move blood through the heat exchanger is the patient’s own heart. Access to the patient’s arteriovenous system for this device will be the same as standard practice for a heart lung machine.

The proposed device holds tremendous potential for providing life-saving support for trauma patients in both the military and civilian populations. At the present time it is still in the concept and prototyping phase of development. Since the early studies have been accomplished via some ingenious but intuitive work by a team of surgeons, there is no basis for understanding and predicting performance based on a rational model of the device when attached to a patient.