Science and engineering education take on very different meanings under the Next Generation Science Standards. Whereas before these subjects (when engineering was taught at all) typically covered what others had discovered or created, under NGSS they become studies of how to actually engage with each subject. To understand how they interact with each other, as well as with technology and math, we will first address the STEM cycle.
Science and engineering are iterative processes, with engineering utilizing knowledge learned through science to solve problems, and science using what engineering develops to answer ever-deeper questions. Technology, math and knowledge are the bridge that link the two.
The nature of science and engineering change under NGSS, is demonstrated clearly with the STEM cycle in the image above. First, though, it's important to understand the definitions of science and engineering. Science is knowledge from experimentation. Scientists engage in answering questions from experiments by planning and developing them, then coming to evidence-based conclusions.
Engineers use the knowledge scientists gather to solve problems, which they do by prototyping: developing and testing prototypes of new technology (which is anything that solves a problem). Math is at the center of it all because it's our language for communication. And new knowledge obtained through scientific experimentation and use of engineered technology enables the entire cycle. This endless loop is the nature of science and engineering and the way that both are framed in the new standards. You might also call this the cycle of innovation, because the knowledge that scientists develop help engineers solve problems, and technology that engineers produce helps scientists answer and ask new and different questions.
Let's be clear: Science is not about making things bubble. It's not about knowing all the facts. Science is about asking questions to learn more about our world and how it works. Similarly, engineering is not all about building things. Engineering is about solving problems, which they may do tangibly (machines, technology) or intangibly (processes, software).
It's important to be very clear about this because for many people, this is a new way of thinking about science and engineering are; it is critical to the proper understanding of STEM instruction. In fact, to be highly effective, a full understanding of these concepts is necessary because you must transmit these ideas to your students. Only then will they be able to articulate, understand and actually live this cycle themselves in your classroom.