Zdeslav Hrepic

Demonstrating Sound Wave Propagation with Candle Flame and Loudspeaker

The motion of a candle flame in front of a loudspeaker has been suggested as a productive demonstration of the longitudinal wave nature of sound.1 The demonstration has been used also as a research tool to investigate students understanding about sound.2–4 The underpinning of both applications is the expectation of a horizontal, back-and-forth vibration of the flame around its upright position. Unlike experts, who regularly anticipate this outcome, students with no previous formal knowledge typically anticipate that the flame will lean away from the speaker.

What Is the Half-Life of Basketball Teams?

What do basketball teams have in common with radioactive nuclei? It turns out, there is more here than first meets the eye. The National Collegiate Athletic Association (NCAA) basketball tournaments feeds fans craving when NBA competitions are not in swing, and the college tournament time has been referred to as “March Madness” or the “Big Dance”1 as many fans participate in “bracketing,” i.e., predicting winners.

Pedagogy and/or technology: Making difference in improving students’ problem solving skills

Pen input computers combined with interactive software may have substantial potential for promoting active instructional methodologies and for facilitating students’ problem solving ability. An excellent example is a study in which introductory physics students improved retention, conceptual understanding and problem solving abilities when one of three weekly lectures was replaced with group problem solving sessions facilitated with Tablet PCs and DyKnow software [1,2]. The research goal of the present study was to isolate the effect of the methodology itself (using additional time to teach problem solving) from that of the involved technology. In Fall 2011 we compared the performance of students taking the same introductory physics lecture course while enrolled in two separate problem-solving sections. One section used pen-based computing to facilitate group problem solving while the other section used low-tech methods for one third of the semester (covering Kinematics), and then traded technologies for the middle third of the term (covering Dynamics). Analysis of quiz, exam and standardized pre-post test results indicated no significant difference in scores of the two groups. Combining this result with those of previous studies implies primacy of pedagogy (collaborative problem solving itself) over technology for student learning in problem solving recitations.Pen input computers combined with interactive software may have substantial potential for promoting active instructional methodologies and for facilitating students’ problem solving ability. An excellent example is a study in which introductory physics students improved retention, conceptual understanding and problem solving abilities when one of three weekly lectures was replaced with group problem solving sessions facilitated with Tablet PCs and DyKnow software [1,2]. The research goal of the present study was to isolate the effect of the methodology itself (using additional time to teach problem solving) from that of the involved technology. In Fall 2011 we compared the performance of students taking the same introductory physics lecture course while enrolled in two separate problem-solving sections. One section used pen-based computing to facilitate group problem solving while the other section used low-tech methods for one third of the semester (covering Kinematics), and then traded technologies for ...

So Why Would a Pigeon Stand on One Leg (or Limp Without Hurting)

While we still do not have a definitive answer about the reason(s) for which birds stand on one leg,1 a list of suggestions has been offered both by expert ornithologists and amateur birdwatchers. We offer a perspective grounded in statics and rotational dynamics that has not been suggested in the literature. The discussion has implications for bird study, and it can also be used as a rich context for teaching statics and dynamics topics at levels ranging from conceptual courses to advanced mechanics.