There was a positive relationship for fourth grade students between the number of years they attended preprimary education and their mathematics achievement (Exhibit 5.14) and science achievement (Exhibit 5.15). According to their parents, a majority of fourth grade students across countries had attended three years or more of preprimary school—56 percent. Beyond that, on average, 17 percent had attended two years, 15 percent attended one year or less, and 12 percent did not attend preprimary school.

The students who attended three years or more had the highest average mathematics achievement (509), and those with less preprimary school attendance had successively lower average achievement (495, 483, and 464, respectively). There was a similar pattern with regard to science achievement, with an average of 500 for those who attended three years or more, and successively lower science achievement for those with less preprimary attendance (489, 472, and 452, respectively).