If extra paper is not considered at the interface, it is the sum of the areas of six sides of the packaging box, including:

2* (length * height+width * height+length * width) = wrapping paper area.

Knowledge expansion:

Teaching Design of "Packaging Knowledge"

Teaching material analysis:

Packaging Knowledge is a comprehensive practical course. Students learned the calculation of surface area of cubes and cuboids, and the knowledge of merging and splitting of cubes and cuboids. This lesson is to organize students to explore, discover and summarize the laws, carry out mathematical activities about "packaging knowledge", and focus on solving the mathematical problems of how to save wrapping paper in the activities.

Teaching objectives:

(1) Knowledge and skill goal: Understand different packaging methods, and use the knowledge of surface area to explore the optimal strategy of minimizing the surface area of multiple identical cuboids. Experience the diversification of strategies and develop the idea of optimization.

(2) Process and Method Objectives: Develop hands-on operation ability and spatial imagination concept, cultivate the ability to actively think and explore laws, and solve simple practical problems in different ways. Experience the basic process and method of solving problems and improve the ability of solving problems.

(3) Emotion, attitude and values: carry forward the national spirit and infiltrate the consciousness of saving. Understand the application of packaging knowledge in life, experience the connection between mathematics and life, and improve the interest in learning mathematics.