Sunday, Yomi, 		Dharriyat, Salami, 		Agnes, Olorunnishola, AND 		Kennedy, Shuaibu.
" Development and Assessment of Upper Basic Students’ Conceptual Understanding of Mathematics Knowledge Using Two-Tier Diagnostic Test in Kogi State, Nigeria" <em>NIU Journal of Educational Research</em> [Online], Volume 12 Number 2 (23 June 2026)