One step of the published mechanism of the hydrogen peroxide iodine-clock reaction is called into question by the result of an experimental attempt (predicated on that mechanism) to integrate that reaction into the elephant's toothpaste demonstration to reveal and control its iodine side product. Under conditions that were a hybrid of those…

In 1879, in the midst of the debate between English and continental scientists about the nature of cathode rays, William Crookes conducted an experiment in which a small mill or "paddle wheel" was pushed along tracks inside a cathode ray tube (CRT) (similar to that shown in Fig. 1) when connected to a high-voltage induction coil. Crookes…

Since long time ago, many authors advocated for more presence of physics history in physics teaching and learning in order to give students a better vision of the "nature of science", in other words, to let them learn not only established physics knowledge but also the ways of how physicists managed to get that knowledge. Generally,…

This activity discusses a unit exercise in which a physics practical was implemented during a laboratory session. The lab practical design was centered on Newton's Second Law. The practical was implemented in a high school setting. Further, through the administration of both a pre and post test we were able to assess the effectiveness of the lab…

A simple blind spot activity has been devised to help students discard misconceptions about image formation by lenses. Our hands-on experiment, in which students determine the location and size of their blind spots, is suitable for various age groups at different educational levels. The activity provides an opportunity to teach students how to…

Animations of molecular structure and dynamics are often used to help students understand the abstract ideas of chemistry. This qualitative study investigated how the features of two different styles of molecular-level animation affected students' explanations of how sodium chloride dissolves in water. In small group sessions 18 college-level…

Students use their preschool experiences to form personal theories about the world and rarely correct misconceptions even when new information is presented. This article describes an elementary science teacher's efforts to help fifth and sixth graders revise personal electricity theories, based on experimentation. There is no simple way to…

Plant tropisms--their directional movement in response to stimuli--are a fundamental concept in plant science and excite students because they are the observable signs of life in plants. Unfortunately, the precollege teaching literature is full of tropism misconceptions. An inexpensive clock clinostat is invaluable for student gravitropism and…

Diffusion and osmosis are central concepts in biology, both at the cellular and organ levels. They are presented several times throughout most introductory biology textbooks (e.g., Freeman, 2002), yet both processes are often difficult for students to understand (Odom, 1995; Zuckerman, 1994; Sanger "et al.", 2001; and results herein). Students…