Less than a year after the Soviet Union launched Sputnik 1, the first artificial Earth satellite, on October 4, 1957, the US Congress passed the National Defense Education Act, which allocated billions of dollars for the purpose of improving math and science education. One result was the establishment of the Biological Sciences Curriculum Study by the American Institute of Biological Sciences. A geneticist, Hiram Bentley Glass, chaired the first Steering Committee. The BSCS, made up of mainly professional biologists, decided to focus on secondary school biology, mainly at the tenth-grade level, and collaborated with high school educators and administrators to develop and implement new curriculum materials.
The BSCS team, led by Principal Investigator Roger Bybee, developed a lesson model based on constructivism to advance the teaching of science. Constructivism proposes that learners need to build their own understanding of new ideas. The model describes a teaching sequence that can be scaled for entire programs, specific units, or individual lessons. They called it the BSCS 5E Instructional Model, with five different stages of a teaching sequence. These stages would be done across several school days and not necessarily in a single class period for each stage. The five stages of the BSCS 5E Instructional Model are designed to facilitate the process of constructivism in students by providing connections among student activities and bringing coherence to different teaching strategies. The five stages are: Engage, Explore, Explain, Extend (or Elaborate), and Evaluate.
The purpose for the engagement stage is for teachers to capture student curiosity about the phenomena and to get them personally involved in the lesson, while assessing the prior knowledge of the students. Students are introduced to the lesson topic and start making connections between their previous and current learning experiences. This lays the organizational foundation for upcoming activities.
The purpose for the exploration stage is to give students a chance to build their own understanding by participating directly in an activity involving the phenomena. As the students work together in teams, they build common experiences through communicating and sharing. The teacher is a facilitator, guiding the focus of the students through questioning and observation as they actively learn through inquiry and engineering challenges. Ideally, the students, through guided exploration, make hypotheses, design their own investigations, test their own predictions, and draw their own conclusions.
The purpose for the explanation stage is to ask the students to communicate what they have discovered so far and to figure out its meaning as they build their understanding of the phenomena. Student discussions allow for the placing of events into a logical sequence and occur between peers. The teacher, as the facilitator, may refine the understanding of students by guiding the discussion topics to include vocabulary in context and to redirect any student misconceptions.
The purpose for the extension (or elaboration) stage is for the teacher to ask students to use their new knowledge in unfamiliar but similar situations. At this stage, their understanding of the phenomena is challenged and deepened as the students expand on the learned concepts and make connections to related concepts. The students apply their understanding to the world around them in new ways as the teacher guides them toward the next lesson topic.
The purpose for the evaluation stage is for both teachers and students to determine how much understanding of the phenomena has taken place. It is an ongoing process where the teacher observes each student’s knowledge and depth of understanding. Assessment should take place at points throughout the continuum of the teaching process and not within its own set stage. Evaluation may include teacher observations and rubrics as well as students demonstrating their understanding with projects, interviews, and portfolios.
