Bramlett and Drake (2013) suggest that the ability of teachers to teach proof is crucial for students to learn and develop formal and informal proofs. Teachers need to be involved in the process of proving and have a firm understanding of the critical role of proofs in order to effectively engage their students in proving activities. It is unrealistic to expect K-12 teachers to educate students on proof if they themselves are not given opportunities to engage deeply in the process of proving and understand its significance (Bramlett & Drake, 2013). According to McClain (2010), it is important for teachers to help students understand proof and engage in proving tasks. However, there has been little research on how to teach proof in secondary school mathematics. Steele (2012) suggests that teachers should have the knowledge and skills to identify whether mathematical arguments constitute proofs or not and determine what counts as proof across different representations. Pedagogical beliefs toward proof may be influenced by teachers' beliefs about the nature and role of proof in mathematics, its role in school mathematics, and their beliefs about themselves as mathematical thinkers. In this case study, the researchers leveraged a qualitative method -- case study -- to study a pre-service teachers' belief about the process of proof and the role of visualization and technology in teaching proof. [For the complete proceedings, see ED657822.]