Preschool teachers should teach science through exploration, observation, and hands-on activities rather than lectures. Activities like singing songs about body parts, playing Simon Says to learn parts, and using senses to identify objects help engage preschoolers. Lesson plans should integrate music and involve tracing bodies, naming parts, and moving to develop understanding of science topics like life cycles and the human body in a developmentally appropriate way. Vygotsky's theory emphasizes that social interaction and scaffolding assistance from teachers are important for cognitive development in young children.