American children are particularly interesting-math scores are not the best, but most children still regard math as their favorite subject. This enthusiasm is one of the most successful places in American mathematics education, which is related to their great emphasis on "solving practical problems with mathematical games".

Cryptography is a subject that studies how to transmit information secretly, involving mathematics, computational science and programming. Stanford University's open cryptography course is very popular. Professor Dan Boneh, lecturer of the Department of Computer Science and head of the Department of Cryptography, won the grand prize in the field of cryptography and identity encryption applications. Driven by this cutting-edge topic and atmosphere, many primary and secondary schools in the United States now adopt project-based learning (PBL) to stimulate students' scientific thinking with passwords.

Understand the working principle of passwords in the technical and financial fields, and how to compile and decode passwords. Through real cases in class and interesting challenges after class, students can appreciate the beauty of numbers, stimulate their interest in mathematics learning, improve their logical thinking ability, and finally become a skilled "password interpretation expert".