More than half of first-year high school students in the Seoul area were found to be at Levels 1 and 2—the lowest levels—on a math proficiency diagnostic test. The proportion of students at the lowest math proficiency levels jumps 2.4-fold as students progress from sixth grade to second grade in middle school, leading to calls for targeted remedial measures during the transition from elementary to middle school.
According to the “Results of the Seoul Student Literacy and Numeracy Diagnostic Test (S-PLAN)” received on October 2 by Rep. Kim Moon-soo of the Democratic Party of Korea, a member of the National Assembly’s Education Committee, from the Seoul Metropolitan Office of Education, the percentage of students in Level 1 (lowest) in math skills among first-year high school students in 2025 was 17.3%, while 36.0% were in Level 2. Compared to 2024, the proportion in Level 1 increased by 3.6 percentage points and that in Level 2 by 8.4 percentage points, bringing the combined total for Levels 1 and 2 from 41.3% to 53.3%—a rise of 12.0 percentage points in just one year. The proportion of students at Level 4, the highest level, decreased by 8.9 percentage points, from 34.2% to 25.3%.
S-PLAN is a diagnostic assessment administered to fourth- and sixth-grade elementary students, second-year middle school students, and first-year high school students in Seoul; in 2025, approximately 100,000 students from 591 schools participated. The Office of Education estimated that the “mode effect”—resulting from the administration of 2025 paper-based test items via CBT at sample schools in preparation for the full transition to computer-based testing (CBT) in 2026—played a significant role in the decline in the correct answer rate. Similarly, when the Programme for International Student Assessment (PISA) switched to CBT in 2015, South Korea’s math score dropped from 554 points to 524 points.
By grade level, the decline in mathematical proficiency began in earnest upon entering middle school. In 2025, the proportion of students at Level 1 in mathematical literacy was in the single digits—5.0% for fourth-grade elementary students and 5.7% for sixth-grade elementary students—but surged to 13.7% for second-year middle school students and 17.3% for first-year high school students. The proportion of students at Levels 3 and 4—considered the stable range—remained at approximately 80% across all grades for literacy, but for mathematical proficiency, it dropped from about 80% in elementary school to below 60% in second-year middle school and first-year high school.
The rate of improvement also slowed. The average increase in scale scores between grade levels remained consistent for reading literacy: 92 points from 4th to 6th grade, 78 points from 6th grade to 2nd grade of middle school, and 78 points from 2nd grade of middle school to 1st grade of high school. In contrast, for mathematical skills, the improvement was 72 points, then 61 points, and dropped significantly to 28 points in the period from 8th grade to 10th grade. The average correct answer rates for the subdomains of 10th-grade mathematical skills—Shapes and Measurement at 50.9% and Data and Uncertainty at 52.8%—remained in the low 50s.
As students advanced to higher grades, the number of students who submitted their exams early without fully solving the problems also increased. The number of students who submitted their answers within 10 minutes of the exam starting surged from 23 in 4th grade and 24 in 6th grade for mathematical skills to 135 in 2nd grade middle school and 245 in 1st grade high school. The number of first-year high school students who submitted their math tests early was approximately 2.3 times that of those who did so for reading comprehension (108 students).
The Office of Education views a lack of reading comprehension—the inability to understand long word problems—as one of the main causes of declining math skills, and has decided to develop supplementary materials that train students in a “4-step reading strategy” using word problems and descriptive passages from textbooks and assessment questions: “identify key words → separate conditions → restate the problem → set up an equation.” —a four-step reading strategy—using word problems and descriptive passages found in textbooks and assessment questions. It will provide a budget of approximately 2.5 million won per school—totaling 500 million won—for customized programs at participating schools. S-PLAN is scheduled to be expanded nationwide under the Ministry of Education starting in 2027.
Assembly Member Kim Moon-soo stated, “The reality that more than half of high school freshmen remain at Math Proficiency Levels 1 or 2 and submit their answers within 10 minutes is the result of a combination of math learning deficits that began in the upper grades of elementary school and literacy issues that prevent them from comprehending long word problems,” and “We must significantly strengthen intensive remedial education linked to reading comprehension starting from the transition period between sixth grade and second year of middle school, when the math proficiency gap begins to widen,” he emphasized.
