For many grandchildren their grandparents are "special" people, and the time they spend together often generates memorable experiences and conversations that are educational. Yet society underestimates the impact that grandparents have as mentors and role models for children. Through spontaneous, shared activities grandparents support the science and technology learning of their grandchildren. In this article, informed by socio-cultural theory, we draw on Vygotsky's everyday and scientific concepts, as well as interpsychological and intrapsychological functioning. Analysis involved highlighting the important co-construction that occurs through these informal intergenerational interactions. Our findings highlight the significance of these shared conversations in relation to children's emerging everyday concepts in science and technology. The analysis identifies the significant role played by older generations in developing children's understanding of natural phenomena and how things work. Implications of our study highlight the benefits for children when the everyday concepts they bring with them into the classroom are valued. (Contains 3 figures and 1 footnote.)