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Teacher Expectations for the Disadvantaged

It is widely believed that poor children lag in school because they are members of a disadvantaged group. Experiments in a school suggest that they may also do so because that is what their teachers expect...

By Robert Rosenthal and Lenore F. Jacobson

Oxygen in Steelmaking

The injection of pure oxygen into a mixture of molten iron and scrap greatly speeds up the refining of steel. A process based on the use of oxygen is rapidly replacing the open-hearth method of steelmaking...

By Joseph K. Stone

Photon Echoes

Experiments in which two light pulses are aimed at one end of a ruby crystal and three light pulses are detected emerging from the other end are explained in terms of the crystal's inherent "phase memory"...

By Sven R. Hartmann

The Confirmation of Continental Drift

After years of debate many lines of evidence now favor the idea that the present continents were once assembled into two great land masses: Gondwanaland in the south, Laurasia in the north...

By Patrick M. Hurley


Bacteria that may barely infect a trivial wound can produce enough toxin to cause the severe and often fatal symptoms of this disease. Tetanus is hard to treat, but it could be eradicated by immunization...

By W. E. van Heyningen


The tiny grains that carry the male genetic material of plants are closely studied with, among other instruments, the scanning electron microscope. Their baroque architecture raises fundamental questions...

By Patrick Echlin

The Qanats of Iran

Some 3,000 years ago the Persians learned how to dig underground aqueducts that would bring mountain ground water to arid plains. Today the system provides 75 percent of the water used in Iran...

By H. E. Wulff

The Sexual Life of a Mosquito

Modern methods of insect control call for detailed knowledge of an insect's physiology and behavior. Reproduction in Aedes aegypti, the yellow-fever mosquito, is surprisingly elaborate

By Jack Colvard Jones


  • 50 and 100 Years Ago: April 1968

  • Science and the Citizen: April 1968

  • Letters

    Letters to the Editors, April 1968

  • Recommended


  • Mathematical Recreation

    Mathematical Games

  • Amateur Scientist

    The Amateur Scientist

  • Departments

    The Authors

  • Bibliography

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