Sight-reading is basically a comprehensive exam on aural skills. In order to learn/improve one’s sight-reading skills, one must ultimately learn and improve aural skills.

I went looking for the same thing for myself, except for audition purposes. After spending hours trying to find a proper comprehensive and progressive sight-singing course for free on YouTube, I came to the conclusion that investing in a comprehensive methodology book that had online audio access would be the most effective for me.

Sight reading is like learning to read. With rare exception, (I know one person who can sight read anything but cannot read music), you have to start with the fundamentals and practice a little bit every day until you become proficient and can hear the music in your head when you look at it. You can use hymnals for practice (I practice with the psalm refrains in old Breaking Bread hymnals), instrumental etude books (my oboe teacher makes me sight sing in our lessons before I play anything the first time), and I also practice scales, arpeggios, intervals, etc with a tuner and drone to reinforce good intonation and improve pattern recognition. In the end music is all patterns that repeat themselves in different keys. Eventually you become proficient in memorizing all of them.

It’s great that choir members want to take initiative to improve their skills. It’s unfortunate that this isn’t given greater priority in parish choirs. I hate how church choirs are often just treated like a ministry anyone can do and they can’t advance in skill and sing from the Church’s rich patrimony of sacred music because of lack of skill and willingness to practice and improve.

I know of a director who has budgeted to help pay for voice lessons.

I’m not even talking about voice lessons. I’m just talking about developing musicianship skills. I never really took voice lessons. Some of the secular choirs I was in offered a set number of private vocal coaching sessions with vocal instructors, but that was it.

Imagine if Dioceses pooled their professional music resources and had annual or semi annual workshops for choir members that had seminars for each skill level.

. I hate how church choirs are often just treated like a ministry anyone can do and they can’t advance in skill and sing from the Church’s rich patrimony of sacred music because of lack of skill and willingness to practice and improve.

I wish more people understood this.

I get it, because it is a ministry. But it's highly skilled and specialized, and it takes a lot of time and effort to develop. It's exactly this attitude that results in a lot of mediocre church choirs. Is having a mediocre choir better than having no choir? Depends who you ask. I personally would rather have no music than off-key, badly executed music.

Imagine if Dioceses pooled their professional music resources and had annual or semi annual workshops for choir members that had seminars for each skill level.

Wouldn't that be wonderful?

SponsaChristi mentioned books. For a structured and gradual approach, Kodaly's Elementary Exercises is good for less-skilled choir members, and Ottman's Music for Sight Singing is good for people who need more challenge.