The rise time test (along with the settleometer procedure) is used to monitor sludge behavior in the secondary clarifier of an activated sludge system. The test monitors the effect of the nitrification/denitrification process and aids the operator in determining optimum clarifier sludge detention time and, to some extent, optimum degree of…

The settleometer test is used to indicate the solids-liquid separation (downtime) capability of sludge, most commonly on activated sludge entering the secondary clarifier and aerobic digesters. Designed for individuals who have completed National Pollutant Discharge Elimination System (NPDES) level 1 laboratory training skills, this module…

A commonly used test for determining filterability of conditioned sludge is the specific resistance (Buchner funnel) test. The sludge is filtered through filter paper using a Buchner funnel, and the time needed to obtain a given volume of filtrate (or for cake residue to begin to crack) is measured. The shorter the time, the better the…

Describes an experiment, easily repeated in the classroom, designed to determine whether members of the species Drosophila melanogaster show selective preference in choice of mates. (PEB)

Presented is a discussion focusing on teaching radioactivity in the schools. The author suggests equipment available and experiments that can be performed. (PEB)

A number of activities are described by which a class can collect biological data about the students in the class. Brief instructions are given. (RH)

Directions are given for activities designed to help children realize that linear measurement is continuous, that it involves the repeated use of a unit in the same way each time, and that measurement is approximate. Non-standard units as well as standard units are included. (DT)

The article provides helpful hints to the teacher who wishes to develop learning centers in his classroom. The author defines a learning center and tells how the center can be managed, how it should be begun, and the benefits it offers to the teacher. (HMD)

The authors promote the position that the benefits tend to exceed the pitfalls of dual facilitation of intense small group experience and should become a more standard feature of laboratory training, for reasons of new trainer development, better learning experience for participants, and continuing skill development of experienced trainers. (AJ)

A teacher and a librarian cooperated in designing a high school history independent study project. (PF)

A new approach to a research-oriented general chemistry laboratory is described. Objectives for the laboratory program are specified, details are provided concerning the program design, and the results of an experiment to evaluate the program are reported. (DT)

Describes an experiment designed to familiarize students with the operation of a precision spectrophotometer, the effects of changes in operating variables, and the characteristics of such components as sources and detectors. (SLH)