The acronym STEM (Science, Technology, Engineering, and Mathematics) has been used very frequently in educational institutions over the last decade. It makes sense to combine them under one term, as those subjects are organically linked by nature.
When a school decides to use this term in their program, it is because it has been demonstrated that by having an interdisciplinary approach to those subjects, the retention and understanding of concepts is amplified. Student engagement and motivation is increased, as they can see real connections with the world around them. Often, they are using those skills to build artifacts that have an impact.
For example, in 3rd Grade, during the unit called Share the Planet, students study the basics of electricity: what are insulators and conductors, how to light a lamp, and what are the dangers of short circuits.
When they are done, they create a program in Computer Science to illuminate a drawing done in art class using LEDs, wires, and a small microcontroller. As they previously studied electricity, they are better equipped to solve problems when they build their circuits. By carefully designing their learning progression, teachers give the students the opportunity to practice skills they learned in a different environment, reinforce their new knowledge and skills, and connect them to real-life projects.
While the spiraling approach helps to interconnect different subjects with one another, it is also of great use within the same subject.
For example, in one of the first units in 4th Grade computer science, students are introduced to programming conditions. They spend time deeply understanding this concept using Scratch, a high-level blockbased visual programming language used for young programmers beginning their education. Later during the year, they will revisit this concept in another context when they design a timer for a toothbrush using a microcontroller that they designed the previous year. Taking the controller they created in 3rd Grade, and the knowledge of the timer from 4th, the students use the value measured by a sensor in a condition to trigger the action they desire.
Interweaving the different subjects, or the different topics from within the same subject but from different years, builds a greater foundation for learning for our students. They create a deeper, real-world understanding of the information that they can build upon throughout the rest of their education and everyday lives.