Covariate adjustment can increase the precision of estimates by removing unexplained variance from the error in randomized experiments, although chance covariate imbalance tends to counteract the improvement in precision. The author develops an easy measure to examine chance covariate imbalance in randomization by standardizing the average…

Gravitational light deflection, predicted by general relativity, is a fascinating phenomenon with numerous important applications in astronomy, astrophysics and cosmology. At first sight, there is no analogous effect in electrodynamics because Maxwell's equations are linear and, therefore, a photon does not interact with the electromagnetic field…

Four experiments investigated the effects of transactional content on temporal and probabilistic discounting of costs. Kusev, van Schaik, Ayton, Dent, and Chater (2009) have shown that content other than gambles can alter decision-making behavior even when associated value and probabilities are held constant. Transactions were hypothesized to lead…

Solid potassium permanganate (KMnO[subscript 4]) is shown to react in a variety of ways with small organic amines or oxygenated compounds depending on whether they are liquids or solids and whether water is present. In particular, its reaction with solid oxalic acid dihydrate can be initiated by the moisture in one's breath, making an intriguing…

A laboratory exercise using [superscript 27]Al NMR spectrometry to study the tetrahedral tetrahaloaluminate anions has been developed. Spectra of the homoleptic complexes [AlX[subscript 4]]-and the dihalide anions [AlX[subscript 4]Y[subscript 4-n]]-(X, Y = Cl, Br, or I) are acquired, then the pairwise-additivity concept developed by Vladimiroff…

The present study focused on children's deductive reasoning when performing the Latin Square Task, an experimental task designed to explore the influence of relational complexity. Building on Birney, Halford, and Andrew's (2006) research, we created a version of the task that minimized nonrelational factors and introduced new categories of items.…

Despite being proficient tool users, young children have surprising difficulty in innovating tools (making novel tools to solve problems). Two experiments found that 4- to 7-year-olds had difficulty on two tool innovation problems and explored reasons for this inflexibility. Experiment 1 (N = 51) showed that children's performance was unaffected…

Sidman (1994) noted that the existence of a member that is common to more than one class may produce either class merger (union) or class intersection. A multiple-selection, matching-to-sample test was developed to examine the conditions under which these outcomes occur. Test trials each required three conditional discriminations involving…

We describe the projects "Eratosthenes 2009" and "Eratosthenes 2010 America," carried out during the International Year of Astronomy (2009) in Argentina and with almost all the countries in North and South America during 2010. More than 15000 students at more than 200 schools each year determined the radius of the Earth using…

Plastic water bottles are convenient containers for demonstrations of gas properties illustrating Boyle's law, Charles's law, and Avogadro's law. The contents of iron-based disposable hand warmer packets can be used to remove oxygen gas from the air within an unfilled plastic water bottle.

A student activity that focuses on the isolation of glucoraphanin from broccoli using preparative high-performance liquid chromatography (HPLC) is presented here. Glucoraphanin is a glucosinolate, whose byproducts are known to possess anticancer properties. It is present naturally at high levels in broccoli and other "Brassica" vegetables. This…

Schlieren imaging is a method for visualizing differences in refractive index as caused by pressure or temperature non-uniformities within a medium, or as caused by the mixing of two fluids. It is an inexpensive yet powerful and straightforward tool for sensitive and high-resolution visualization of otherwise invisible phenomena. In this article,…

Paramagnetic and diamagnetic materials are now generally known as the "Cinderella" materials of the magnetic world. However, susceptibility measurements made on these materials in the past have revealed many details about the molecular bonding and the atomic structure of the so-called "transition" elements. Indeed, the magnetic moment of neodymium…

How effective is training frogs to jump? This is perhaps the most frequent question in biology that is subjected to statistical analysis: does a treatment make a difference? One can examine whether there is indeed a training effect, by first assuming the opposite. That is, the authors assume that training has no effect on the mean distance jumped.…

Stimulus over-selectivity refers to behavior being controlled by one element of the environment at the expense of other equally salient aspects of the environment. Four experiments trained and tested non-clinical participants on a two-component trial-and-error discrimination task to explore the effects of different training regimes on…