To address the challenges of teaching and learning among multilingual elementary students, the Philippines, a multilingual country with over 180 languages, implemented the Mother Tongue-Based Multilingual Education (MTB-MLE). Studies on the use of mother tongue have reported positive results among students who share a common language. However, in highly multilingual places, mother tongue use poses a challenge to students whose mother tongues differ from the one used in the classrooms. Using non-participatory observations, this study gathered data from a highly multilingual city in the Philippines to determine how teachers and students use languages during the teaching and learning of science. It reveals that the participants used translanguaging in accomplishing communicative functions needed in teaching and learning science. Subsequently, the study proffers the legitimization of translanguaging as it is pedagogically beneficial to both the teachers and the students in multilingual elementary classrooms.