This post includes a video showing single slit diffraction of a LASER beam.  The derivation develps formulas to find the diffraction maxima and minima as a function of angle.

Vocabulary:  You need to be able to distinguish between these words, what they mean, and be able to draw diagrams for each.

(we’ll worry about Interference later)

You need to know:
Huygen’s principle of point radiators.
Similar Triangles
Small angle approximation

Derivation of position of maxima and minima using Huygen’s Principle of Wavelets

Diffraction_Derivation_Part-1: Finding Maxima


Difraction Part 2-Full Width of Central Max

Single Slit Diffraction explained.