Fractions are the basis for most higher-level mathematics. Students need to master the numerical values in earlier grades to tackle topics like algebra later. There’s only one hitch: Fractions can ...

Hydrologists measure large amounts of water in acre-feet – an acre of water one-foot deep, or 326,000 gallons. In an average year, 200 million acre-feet of water fall on California as rain or snow.

In an average year, 200 million acre-feet of precipitation falls on California as rain or snow. (Hydrologists measure large amounts of water in acre-feet — an acre of water one-foot deep, or 326,000 ...