Secondary 2 – Biology: Food Test Experiment
In this week’s Biology lesson, Secondary 2 students conducted a hands-on laboratory investigation to identify the presence of protein, sugar and starch in common foods such as tofu, potatoes and biscuits. Using scientific testing methods, they applied three different reagents: Benedict’s solution for sugar, Biuret reagent for protein and Lugol’s iodine for starch to observe chemical reactions that revealed the nutrient content of each sample.
The activity began with students predicting which food might contain each nutrient. They then carefully followed laboratory procedures: adding drops of the reagents to the food extracts and gently heating the samples in a sugar test. As reactions took place, students observed colour changes: Benedict’s turning from blue to orange indicated the presence of sugar, Biuret turning purple showed the presence of protein and Lugol’s changing from brown to dark blue or black revealed the presence of starch.
After recording their observations, students analysed the data and discussed their findings in small groups. They discovered that potatoes contained starch, tofu was rich in protein and biscuits had both sugar and starch. The discussion encouraged them to think critically about how nutrients support body functions and how different foods contribute to a balanced diet.
Through this experiment, students not only strengthened their understanding of biological concepts but also practiced essential scientific inquiry skills such as hypothesizing, observing, analysing and concluding. The lesson concluded with a reflection session where students connected their laboratory findings to everyday food choices, demonstrating how science learning can truly shape healthy living. ***
