The Vowel Pyramid clearly states all of the most common vowels in an easy to understand chart. While the IPA chart is useful, it can sometimes be confusing because not all of the vowels are always used, nor does it provide English support language for each vowel. It also includes how the vowel is formed and compares it to other vowels.
This chart is great as a print out for students or as a large visual in the classroom. Additionally, the Latin vowels are highlighted, as those tend to be the most common vowels that choir teachers relate to.