An absorption line at 900 nm has been observed in Perspex. Samples of 1 and 2 cm thickness were used and the integrated absorption (line width times peak absorption) of the line was proportionate to the thickness. Facilities for lowering the sample temperature were not available and therefore both measurements were carried out at room temperature.…

It is important that students understand the role the ocean plays in mitigating climate change, and how every person on this planet is uniquely connected to the ocean. Identifying these connections can be challenging for students in rural or underserved areas, many of whom do not live by, or interact with, the ocean. Through the use of the board…

When sound waves are taught at the secondary level, the speed of propagation of sound is one of the most important characteristics to be analyzed. However, it is very common in textbooks that the value of sound speed in air is considered constant regardless of the experimental conditions. The great question is that since sound is a mechanical…

Students make and test a seemingly impossible material made from ice and sawdust that had been developed for possible emergency use during the Second World War. It was open to the students to be creative with their methods of testing the viability of such a material. The thought of making a battleship from ice that would gradually melt seems…

We often say that food and fuels "contain" energy, whereas energy is stored in the fuel-oxygen system generated during photosynthesis. This article suggests revised approaches to teaching that make a clear distinction between matter (food, fuel, oxygen) and energy. (Contains 1 table, 5 boxes, and 6 figures.)

Climate change is one of the significant global challenges currently facing humanity. Even though its seriousness seems to be common knowledge among the public, the reaction of individuals to it has been slow and uncertain. Many studies assert that simply knowing about climate change is not enough to generate people's behavioural response. They…

Ocean acidification, a product of CO[subscript 2] absorption by the world's oceans, is largely driven by the anthropogenic combustion of fossil fuels and has already lowered the pH of marine ecosystems. Organisms with calcium carbonate shells and skeletons are especially susceptible to increasing environmental acidity due to reduction in the…

Winds in desert regions form the well-known barchan dunes. Frequently, human settlements are threatened by the migration of these dunes. But why do these dunes move? And how is dune migration in deserts connected to scour development in the vicinity of pylons in river beds or to snow cornices in alpine regions? This paper introduces the topic of…

In this article, the authors describe a two-phase inquiry lesson in which students explore the catalytic activity of amylase on starch (Rungruangsa and Panijpan 1979). In the first phase, students' prior knowledge about the reaction is assessed through a set of directed prompts and small-group discussion, then challenged or reinforced as students…

An experimental system for detecting infrared absorption using the photoacoustic (PA) effect is described. It is aimed for use at high-school level to illustrate the difference in infrared (IR) absorption among the gases contained in the atmosphere in connection with the greenhouse effect. The experimental system can be built with readily…

Ocean acidification is one of the most serious environmental issues facing the planet (e.g., Doney 2006; Guinotte and Fabry 2009). It is caused by excess carbon dioxide (CO[subscript 2]) in the atmosphere. Human activities such as burning fossil fuels put CO[subscript 2] and other heat-trapping gases into the atmosphere, which causes the Earth's…

In this activity, a possible problem related to global warming is clarified by the principle of states of water. The activity consists of an experiment that includes three scientific principles: Archimedes' Principle, the Law of Conservation of Matter, and the fluidity of liquids. The experiment helps students raise questions and open new horizons…

A simple student experiment investigating dependence on air pressure of the attenuation of alpha particles in air is described. An equation giving the pressure needed to absorb all alpha particles of a given energy is derived from the Bethe-Bloch formula. Results are presented for the attenuation of alpha particles from americium 241 and radium…

The change from the state of supercooling to the solid state of ice is called superfreezing. This process is not uncommon and takes place in domestic freezers. It is also easy to reproduce in the laboratory. (Contains 6 figures.)

The role of greenhouse gases in our atmosphere is the subject of considerable discussion and debate. Global warming is well-documented, as is the continually increasing amount of greenhouse gases that human activity puts in the air. Is there a relationship between the two? The simple experiment described in this paper provides a good demonstration…