“…For mathematics, research was equivocal regarding the form of growth trajectory. Recent studies (Lee, ; Murayama et al ., ; Muthén & Khoo, ; Shin et al ., ; Thompson, Kaur, Koyama, & Bleiler, ) found that growth in mathematics achievement at primary and secondary levels was nonlinear with a decelerating growth rate over time. The diminishing growth rate was explained in terms of increasing complexity and abstractness in mathematical concepts required for achievement at higher grade levels (Carraher & Schliemann, ; Lee, ; Shin et al ., ) and of the slowing down of children's cognitive ability for further learning as they grow older (Lee, ).…”