Smartphones are used universally in many areas due to their advanced features. Smartphones are also widely used by teachers and students in education. This research aims to design low-cost and easy experiments for biology lessons using smartphones. Colorimetric measurement was made with a smartphone. Mobile applications were used to read color change values. The amount of sugar in beverages was calculated with the students. They could create standard curves, measure with a smartphone, organize the data, and determine sugar concentration. It was determined that the students had positive thoughts about the activity. Self-confidence results indicated that the activity had a positive effect on students' self-confidence. Although there was a decrease in the mean scores of difficulty, it was revealed that the mean scores were over the “moderate” level. As a result, it can be said that the activity may be easily practiced by teachers and students in biology lessons.