In its program of studies for preschool level, the Secretary of Public Education of Mexico promoted development of four standards of science: Scientific knowledge, applications of scientific knowledge and technology, skills associated to science, and attitudes associated to science. However, to develop this skills and reach out the standards there…

A two-part experiment using bubble rafts to analyze amorphous structures is presented. In the first part, the distinctions between crystalline and vitreous structures are examined. In the second part, the interface between crystalline and amorphous regions is considered. Bubble rafts are easy to produce and provide excellent analogy to recent…

Enzyme kinetics is an essential part of a chemistry curriculum, especially for students interested in biomedical research or in health care fields. Though the concept is routinely performed in undergraduate chemistry/biochemistry classrooms using other spectroscopic methods, we provide an optimized approach that uses a real-time monitoring of the…

Fluorescent proteins are commonly used in cell biology to assess where proteins are within a cell as a function of time and provide insight into intracellular protein function. However, the usefulness of a fluorescent protein depends directly on the quantum yield. The quantum yield relates the efficiency at which a fluorescent molecule converts…

To familiarize first-year students with the important ingredients of a physics experiment, we offer them a project close to their daily life: measuring the effect of air resistance on a bicycle. Experiments are done with a bicycle freewheeling on a downhill slope. The data are compared with equations of motions corresponding to different models…

This series of three practical sessions centers on drugs that inhibit the enzyme acetylcholineesterase. This enzyme is responsible for the inactivation of acetylcholine and has been the target of drugs to treat glaucoma and Alzheimer's disease and for a number of insecticides and warfare agents. These sessions relate to a series of carbamate…

A multistep synthesis of 10-ethyl flavin was developed as an organic chemistry laboratory experiment for upper-division undergraduate students. Students synthesize 10-ethyl flavin as a bright yellow solid via a five-step sequence. The experiment introduces students to various hands-on experimental organic synthetic techniques, such as column…

Two introductory organic chemistry laboratory experiments are described based on the Diels-Alder reaction of 2,3,4,5-tetraphenylcyclopentadienone, which is synthesized prior to or in a one-pot reaction, with styrene. Students are presented with three possible products, the "endo" and "exo" diastereomers and the decarbonylated…

The transport of molecules across biological membranes are critical for most cellular processes. Membrane permeability is also a key determinant for drug absorption, distribution, and elimination. Diffusion, that is, the migration of matter down a concentration gradient, is a simple mechanism by which both endogenous and drug molecules can enter…

Calculating the effective resistance of an electrical network is a common problem in introductory physics courses. Such calculations are typically restricted to two-dimensional networks, though even such networks can become increasingly complex, leading to several studies on their properties. Furthermore, several authors have used advanced…

A laboratory experiment was developed to follow the gelation of a polyvinyl alcohol (PVA) solution upon addition of borax by using rotational viscometry. The rheological properties of the gel were examined, measuring the dependence of viscosity and shear stress on the shear rate. Time-dependent studies were also conducted in which the viscosity of…

The Characterization and Analysis of a Product (CAP) project is used to introduce first-semester general chemistry students to chemical instrumentation through the analysis of caffeine-containing beverage products. Some examples of these products have included coffee, tea, and energy drinks. Students perform at least three instrumental experiments…

At the Deutsches Museum in München, we established in the department of education during more than 35 years a series of historical experiments and constructed apparatus for pedagogic purposes. We use these reproductions mainly for continuing teacher education within our department. At the exhibitions of the Deutsches Museum there exist many…

This article describes an alternative method to determine the refractive index of transparent liquids. The method only requires a laser pointer, a ruler and a modified fish tank.

Optimal foraging theory attempts to explain the foraging patterns observed in animals, including their choice of particular food items and foraging locations. We describe three experiments designed to test hypotheses about food choice and foraging habitat preference using bird feeders. These experiments can be used alone or in combination and can…