Today, the Los Angeles Unified School District has a goal of converting at least 30 percent of every schoolyard to green space, a years-long project that it expects to cost $3 billion. By its own estimate, about 475 schools do not meet that standard and, of them, more than 200 elementary schools have less than 10 percent green space. This analysis does not include school parking lots or truck delivery areas — paved surfaces that are likely to remain that way and raise the temperature around schools.