For an easy introduction to trigonometry suitable for 8th graders, several online resources were recommended. One notable tutorial is "Dave's short Trig course," which can be found at Clark University. Key foundational concepts include the Pythagorean theorem and the basic trigonometric functions: sine, cosine, and tangent. To aid memorization of these functions, mnemonics like "SOHCAHTOA" are suggested, where "SOH" stands for Sine = Opposite/Hypotenuse, "CAH" for Cosine = Adjacent/Hypotenuse, and "TOA" for Tangent = Opposite/Adjacent. Additionally, a combined Algebra and trigonometry tutorial is available at a specified link, providing a comprehensive review for students.