Standard glass pH electrodes are ubiquitous instruments used in research and in classrooms to measure the hydrogen ions present in a solution. While many chemists and educators have communicated ways to support teaching conceptual understanding of solution pH and the function of pH probes and dyes, the community lacks a methodology that enables…

A low-cost and simple setup to measure the densities of liquids is introduced herein. The results and reliability of this setup were evaluated for pure liquids, water-ethanol binary mixtures, and aqueous NaCl solutions. The constructed densitometer provided density values with acceptable relative errors (less than ±3.0%), which were compared to…

Smartphones and tablets are used as experimental tools and for quantitative measurements in two traditional laboratory experiments for undergraduate physics courses. The Doppler effect is analyzed and the speed of sound is determined with an accuracy of about 5% using ultrasonic frequency and two smartphones, which serve as rotating sound emitter…

We develop an Easy Java Simulation (EJS) model for students to experience the physics of idealized one-dimensional collision carts. The physics model is described and simulated by both continuous dynamics and discrete transition during collision. In designing the simulations, we discuss briefly three pedagogical considerations namely (1) a…

The subject of uncertainties (sometimes called errors) is traditionally taught (to first-year science undergraduates) towards the end of a course on statistics that defines probability as the limit of many trials, and discusses probability distribution functions and the Gaussian distribution. We show how to introduce students to the concepts of…

Discusses rapid, approximate methods for the calculation of errors estimates and other statistical results without using the computer. (SK)

Described is the derivation of the relationship between the pH measurement error and the resulting percentage error in hydrogen ion concentration including the use of variable activity coefficients. The relative influence of the ionic strength of the solution on the percentage error is shown. (CW)

Describes an activity designed to introduce concepts of randomness and standard deviation. (CP)

Describes a study used to determine differences in exam reliability, difficulty, and student evaluations. Indicates that when a fourth option was added to the three-option items, the exams became more difficult. Includes methods, results discussion, and tables on student characteristics, whole test analyses, and selected items. (RT)

Discusses the use of linear regression methods to extrapolate experimental data. Describes the method of averages and two weighted least squares. Calculates the error range of each method. (YP)

Describes an experiment designed to teach students to apply the same statistical awareness to instrumentation they commonly apply to classical techniques. Uses propagation of error techniques to pinpoint instrumental limitations and breakdowns and to demonstrate capabilities and limitations of volumetric and gravimetric methods. Provides lists of…

Describes a computerized method to test error analysis that helps motivate introductory physics students to learn the topic. The computer generates a test consisting of four topics from a list of 10 that students should know. Numerical data within realistic ranges are also generated. (JN)

Investigates minimizing errors in computational methods commonly used in chemistry. Provides a series of examples illustrating the propagation of errors, finite difference methods, and nonlinear regression analysis. Includes illustrations to explain these concepts. (MVL)

Contends that the nature of physics has been misrepresented by blurring or ignoring important distinctions between "errors" and "discrepancies" and that dealing with these and related problems can improve students' enjoyment of labs and understanding of physics. Nature of physics, role of experiments, experimental errors, and error analysis are…

Outlines the simple exercise of measuring the length of an object as a concrete paradigm of the entire process of making chemical measurements and treating the resulting data. Discusses the procedure, significant figures, measurement error, spurious data, rejection of results, precision and accuracy, and student responses. (TW)