In this article I explain why I wrote the set of teaching notes on Atomic Absorption Spectroscopy (AAS) and why they look the way they do. The notes were intended as a student reference to question, highlight and write over as much as they wish during an initial practical demonstration of the threshold concept being introduced, in this case inferring the existence of quantized electron energy levels in atoms from class room observations. That is why the notes commence with an overview of how a handheld spectroscope works followed by how they are used for analysing emission spectroscopy observations. The notes decode the noun phrase "Atomic Absorption Spectroscopy" into its individual sequenced components by defining Light Spectra [right arrow] Spectroscopy [right arrow] Emission Spectroscopy [right arrow] Atomic Emission Spectroscopy (AES) [right arrow] Atomic Absorption Spectroscopy. There is every expectation that the teacher delivering this introduction has provided a class set of hand held spectroscopes to the students and a variety of demonstration emission sources such as hollow cathode lamps for mono atomic helium and neon plus a sodium vapour lamp. This concrete experience can now be developed into abstract knowledge and analytical applications in line with the South Australian Stage 2 Chemistry Curriculum Statement (CS) requiring students to understand the principles of AES and AAS. It is also an explicit departure from the more traditional secondary school method of presenting electron energy levels in atoms as a form of ritualized knowledge. The teaching notes that follow show how practical inquiry in the secondary school class room can remain the foundation of scientific method and learning with even the most troublesome of knowledge, such as electron energy levels in atoms. (Contains 2 figures.)