Sometime around 1800 B.C., a Sumerian scholar inscribed a hand-sized clay tablet with a series of cryptic numbers. The unusual tablet, known as Plimpton 322 (below), has provoked years of fevered speculation that it records the thoughts of a Mesopotamian Einstein or a precocious astronomer. Perhaps neither, says Eleanor Robson, an expert in Sumerian writing at Oxford University's All Souls College. She believes the tablet is actually the world's oldest known set of teacher's class notes.

"Most of the excitement from Plimpton 322 hasn't come from historians like me but from mathematicians who see in it all sorts of possibilities," says Robson, who herself started out as a math academic. In contrast to nearly every other Mesopotamian tablet, this one is crammed with algebraically related numbers but contains little in the way of explanatory writing. With few clues to constrain them, mathematicians have freely speculated and interpreted the numbers as a trigonometry table or even as astronomical calculations.

But Robson's analysis of Plimpton 322 shows that it expresses mathematical ideas very similar to those on Sumerian tablets used for instructional purposes. "All the ancient mathematics we have from Plimpton 322's time was written either by students or teachers," she says. Those other tablets may have included essays or word problems; this one probably appears so unusual because it consists of nothing but numerical tests, she says. The tablet could quickly generate a batch of math assignments that have clean, whole-number answers. Based on the efficient layout, Robson judges that the teacher who used the tablet had a flair for organization but probably was no genius.

Courtesy of Columbia University Rare Books and Manuscript Library