In the binary code lessons, students are introduced to the binary number system and its importance in computing. They learn to convert binary numbers to decimal numbers and vice versa. They also practice reading and writing binary numbers through various exercises involving tables of binary and decimal numbers. In the code-cracking activity, students apply their knowledge of binary numbers to decode a secret message written in binary code. They convert groups of 8-bit binary numbers to decimal and then use an ASCII table to find the corresponding characters, ultimately revealing the hidden message. This engaging activity helps reinforce the importance of understanding binary numbers in computing and provides a fun, hands-on way for students to practice their binary number conversion skills.