Improving learning among low-achieving students is a challenge in education. We present results from the first randomized experiment of an inquiry-based remedial science education program for low-performing elementary students in a developing-country setting. Third-grade students in 48 low-income public elementary schools in Metropolitan Lima who score at the bottom half of their school distribution in a science test taken at the beginning of the school year are randomly assigned to receive up to 16 remedial science tutoring sessions of 90 minutes each. Control group compliance with assignment is close to perfect. Treatment group compliance is 40 percent, equivalent to 4.5 tutoring sessions, or a 4 percent increase in total science instruction time. Despite the low treatment intensity, students assigned to the remedial sessions score 0.12 standard deviations higher on a science endline test, with all gains concentrated among boys. We find no evidence of remedial education producing within-student spillovers to other subject areas (math or reading) or spillovers on other students in the classroom. We conclude that low-intensity remedial education can have an effect on science learning among low-achieving students