Germany spends about $15,000 per student per year on school. El Salvador spends about $650. In June, kids in El Salvador's AI tutoring pilot took the OECD's PISA for Schools test and scored comparable to the German national average. Three years ago that would have sounded like a typo. On the 2022 PISA, El Salvador landed near the bottom of every participating country, with 62.8% of its students unable to clear the basic reading bar. Here's what the pilot actually did. 171 public schools got…