TPACK

Teachers need to know the content they are to teach. They will pull up the UEN website to see the facts, concepts and skills their students must learn. But content knowledge (CK) is useless to a teacher without Pedagogical Knowledge (PK). Pedagogical knowledge is the "How To" when it comes to teaching children. As teachers, we first must know what to teach and then how to best teach that material to our students. We cannot effectively teach with one or the other--we must combine CK and PK to know ho to teach in specific content areas.
However, PCK is still not enough. We live in an era of technological discovery. Our students are digital learners. Our teaching and out students' learning will be more efficient if we are able to use technology in our teaching methods or specific content. That's where TPACK comes in.
TPACK combines the WHAT and HOW with TECHNOLOGY. When it comes to CK, students are able to use specific software to help them complete their projects was well as measure and interpret their findings. Technology is incorporated into the content the students are learning. Teachers can also incorporate technology into their pedagogy to help students learn. For example, technology may aid the students by giving them a visual of the content.
Teachers need to know TPACK because today's generation learns digitally--a generation who is so heavily stimulated, who has shorter attention spans, and who needs technology incorporated into their learning if they are going to see the learning experience as relevant to them. I think TPACK is most important because of its ability to hold the students attention and keep them engaged. If students are to really learn, teachers must be familiar with TPACK.