Administration: Individual. The DAB-4 is a revision of one of the most popular individual achievement tests available. Its 8 subtests identify studentsâ strengths and weaknesses across important areas of school achievement. A supplemental manual shows how to probe student responses to obtain information about studentsâ thinking processes and problem-solving strategies.
In 1992, the first evidence of a planetary system other than our own was discovered, orbiting the pulsar PSR B1257+12. Three years later, 51 Pegasi b, the first extrasolar planet around a Sunlike star, was discovered.
When Pluto was discovered by Clyde Tombaugh in 1930, many astronomers were certain that a large planet orbited the Sun beyond Neptune. Instead they found Pluto, which turned out to be small compared to Earth and Neptune, though more than double the size of Ceres, with a diameter of 2,300 kilometers.