Curd is a staple dish used in almost every household. Under the theme 'Food Preservation' in PBL, students of Presidium conducted an activity of setting curd at their home with their parents' help. This activity's objective was to investigate whether using different yogurt starter cultures affects the yogurt that is made. Through this activity, students used their observation skills and explored the causes of changes in food items when left open. They concluded that the bacteria 'Lactobacillus' is essential for making yogurt or curd. They also resolved that lactic acid causes the milk to become more solid or gel-like. In the end, the students concluded that living microorganisms present could turn plain old milk into a yummy yogurt treat.