In this lesson, students learned about calculating the mean and mode of a set of numbers. To find the mean, they added all the values together and divided by the total number of values. They practiced this with examples, such as finding the mean of 11, 12, and 10, resulting in 33 divided by 3, which equals 11. The lesson also explained the mode as the most frequently appearing number in a dataset, highlighting that it is possible to have more than one mode if multiple values appear with the same highest frequency.