This study critically explored Filipino third graders' fluency in science to determine their readiness to comprehend and understand fourth level science, which is taught in English. This mixed design case research purposively sampled 30 third graders from a government-owned elementary school. An oral reading technique using a pre-selected science text passage determined the participants' fluency in science in terms of word recognition and decoding, reading speed, and reading prosody. The results show that our third graders registered low ratings in all the three components of reading fluency. They are categorised as instructional readers of common terms, but are frustrated readers of science terms. They have very low reading speed and based on their reading prosody, more than half of these learners are labelled as non-fluent readers. This resulting dysfluency may be sourced from non-congruence of the complex morpheme and phonemes of English medium compared to the home language of the learners (Filipino). The home language of learners in the Philippines depends on ethno-linguistics grouping, thus a comparative study may be done to extract more information on how to align and help our learners be ready to accommodate level 4 science.