The implementation of Philippine K-12 curriculum brings hope to its educational system on lifting up the poor academic standing of Filipino learners in national and international assessments. With its implementation in 2012, rectification in the instructional practices of science teachers was expected to boost the academic performance of learners. This study aimed to document the instructional practices of teachers and its correlation to the academic achievement of learners in science. A total of 96 teachers and 240 grade 10 learners were randomly selected from 6 schools in provincial and city areas of Albay, Philippines. This was employed through paper survey to the identified respondents with focus in the quantitative aspect of the study. Results revealed instructional practices emphasizing the use of differentiation for planning, spiraling and inquiry in the delivery, and product-focused and differentiation in assessment. Negligence in the use of technology is attributed to effort and preparation issues, age, and computer anxiety. Academic achievement of learners across all curricular programs in science was below the expected standards of the national policy indicating that learning is not at par with the prospects of Philippine K-12 curriculum. Correlational test revealed high relationship between academic achievement and instructional delivery, while moderate relationship to planning and assessment of instruction. It was concluded that teachers were not proficient enough in applying K-12 curriculum instructional practices to enhance the academic achievement of learners. The need to participate in ICT-based seminars in science, and paralleling instructional planning, delivery, and assessment practices were suggested.