This study aimed at investigating grade four students learning at Jimma town, Ethiopia. A cross sectional survey method was employed. Students, teachers and principals were participants of the study. Standardized tests, questionnaire, interview and observation were the instruments used to collect authentic information from the research participants. The collected data were analyzed quantitatively using various statistical techniques and qualitatively categorizing it in to different themes to substantiate the numerical data. The result indicated that students' learning achievement was inadequate in two key subjects namely English and Mathematics which are the core subjects in all education levels of the country. Moreover, there was immense gap among schools and across subjects in students' performance. The major reasons identified were students' background (family socioeconomic status and educational level and mother tongue), students' interest and attitudes towards key subjects (English, Mathematics, Environmental Science and Mother tongue), availability of learning resources and support from school and the families/guardian. From the factors, the most prominent ones are issues related with their home related problems and utilization of the available resources. Thus, researchers recommended that relentless effort should be exerted by all stakeholders to bring students to the level expected of them as stated in the curricula.