Latin American students maintained a low achievement level during the 1990s in spite of huge investments in education, but significant increments in Chilean students' learning were the result of a carefully designed development project implemented in 2001-2002 in a high standard level K-12 school. The use of “interactive learning scripts (guidebooks)" plainly telling the actors (students and the teacher) “activities" to be carried out in each session (grades 1-8) made it easy for teachers to upgrade teaching methods. Less than 5% of the teachers were unable to adapt to the scripted methods while students kept demanding this “easier" way to learn. The external innovation team replicated methods used in the successful massive Colombian Escuela Nueva program, and supervised the project through a monthly two-day visit plus a local team monitoring of every day operations. Given that national test scores in Chile and Colombia are close to the average in Latin America, the findings of this project are relevant for the whole region and may be useful for other developing countries.