The competence and positive disposition development toward mathematic subject has been observed an uphill task to learners across educational endeavors despite its need in life at home, paid work, participation in community and civic life. The Nigerian Education Policy (2013) made numeracy an important aspect of the specific objectives of primary education in Nigeria. However, the teaching-learning processes lithely attend to specification(s) of utilities. In Nigeria, most schools lack instructional materials; the available were mainly ready-made - majorly imported. Information and communication technology has greatly improved teaching and learning yet, observations revealed domination of foreign tongued instructional materials – uneconomical, alien, distractive and inadequate. This study constructs and investigates the effect of a locally produced, customized numeracy package, the Rudimentary Number Skills for Children (RuNS-K) on academic achievement of pupils in computer mediated environment with a view to improve pupils’ performance in numeracy. Pre-test, post-test, quasi experimental research design was adopted. The population consist lower primary school pupils in southwest Nigeria. Multi stage sampling technique was employed to select study sample. One senatorial district, one of the five major cities in the district, three of the eighty-four public primary schools having functional computer laboratories were purposively sampled. An intact class in each school was randomly assigned into two experimental (ICT-integrated Learning Cycle and ICT-integrated Learners-self-controlled) and a comparison groups. Study instruments include the Rudimentary Number Skill for Children (RuNS-K) and the Test of Numeracy Achievement (TNA). The study found localized, customized packages needful for numeracy improvement. It also found significant improvement in numeracy performance in learners in ICT-integrated Learners-self-controlled (ICT- LSC) situation. The study further revealed customized ICT- LSC learning strategy as best influence for retention in pupils. It concludes that, interventions with customized, ICT-integrated learners-self-controlled situation improve learners’ cognition both in performance and retention. Study recommends localized, improvised educational materials development and usage as aid to improving teaching-learning process and the entire education system in Nigeria
