I have loved doing mathematics since I was in elementary school. However, this feeling changed a little bit when I was at secondary school. My mathematics teacher asked me to memorise many formulas and principles related to advanced topics without knowing when I can use those in my real-life. I thought that an advanced topic was really hard to learn because it was commonly abstract concept. Consequently, a student like me would find difficulties how to make it concrete and connect it to the real world. In addition, my mathematics teacher only encouraged us to study mathematics hard in order to achieve high scores in examinations. She rarely explained about the application of mathematics in our daily life. This situation made me less enjoyed learning mathematics. For example, while I was learning calculus that I assumed as an advanced topic, I did not know when I can use it in my life so that I was not motivated to learn it. At the time, I guessed calculus was useless. Calculus was just about patterns, formulas, and calculations without knowing why I needed to learn it. Therefore, this experience has been inspiring me in how I should teach my students in the future.I hoped to explain and show my students about how powerful and useful mathematics can be. Unfortunately, it was really hard to find the connection between mathematics and daily activities, especially for the calculus. My students were questioning when they could use calculus in their life. I became confused and could not give the appropriate answer because I have not known the application of calculus that was relevant to my students' life. I taught calculus using the similar method to my previous mathematics teacher, solving any kind of calculus questions from my own textbooks using the formulas or rules. However, I am interested in exploring and developing the usefulness of calculus in daily life because I want to establish answers for my own previous question, "when I can use it". Hence, when getting the chance to take the developing subject knowledge course, I was excited to focus on some calculus questions using real-life contexts.