Use sound and hearing? During my BA I found it helpful to read aloud every word, recording and playing it back helped even more. Warning: on a crucial assignment I found I was better informed on the author's words than the lecturer setting the assignment who had overlaid with his own interpretation. I made the mistake of correcting the assumption he had made - not done as an undergraduate.

Everyone is good and bad at different things.  I find that instead of trying to do everything, focus on what I am good at.  I did STEM + Econ in school, and ended up in Engineering.  I'd say that the big thing is that knowing that some types of homework can be a major problem/trigger for a full anphant - for example - Read this and write how it makes you feel.  Describe what you see in your imagination when you read this (the answer is "Nothing, its black, just black, always is")  Draw/paint/color anything abstract  any assignment with feelings, imagination, or emotions/empathy.  If they describe something in pure, simple fact format, like "describe the room", and they say "10m x 15m with white walls", vs someone who says "warm with colorful pictures and a carpet as soft as a kitten" that's fine.  Memory works differently in different people.  You know when someone posts a scary picture on social media or TV, and someone says, "I'll never get that out of my head!" As soon as it is gone, the aphant says "what picture??" I don't remember any. I can't get a disturbing picture _in_ my head. 

Some of the webinars that are linked to on this site are absolutely great.  They give a lot of thoughtful feedback about overlapping symptoms and experiences.  Because the aphantasic experiences seems so varied, I would recommend starting from a place of self-reflection.  It sounds like he's really successful, so getting him to tune in to what specifically helps him have success is a great place to start.  That includes success with which subjects and assignment types, but also in environmental components that help him attend in class and how he can set up his homework space to help him focus.  Once he really has an idea of what works for him, then self-advocacy comes much easier.  It's a fantastic skill even to tell a teacher after class, "hey, I'm having a hard time with this particular unit.  I think it might be my aphantasia.  It's a newer kind of neurodivergence, so there's not a ton of guidance on what helps yet, but if you would be game to work through this unit with me, I'd really appreciate it."  We have to remember that young folks (and plenty of adults too) may not think so much about how brains are different.  It can really empower them to know that the educational system is set up primarily for 1 type of brain and it's ok to ask for something different.

I have personal training. I grew up with it and learned many ways of coping with a visual learning environment. I have been for some myself, but haven't found much, but people tell me how they coped with it.  For me, analogies work best. Physics and mathematics were easy because they don't live in the physical plane. I have also found that everything has core structures that may share similar parts with other fields of existence.  Thank you for what you do, I wish the best of luck to you and your students. Anything I can assist with feel free to message me or email me at [email protected]. 

An excellent question as a teacher of final year International Baccalaureate ( a bit different from your Upper Sixths),  I would love to know the answer myself. But as a self-identified aphant, I would encourage the following a) as for all students, remind this student that exploring his own learning style is worth the time. While so many students now fall for the "I am a visual learner" trap, he should make a very serious attempt to note where/how he learns best in each subject. For example, I learned despite all research indicating that this is not a useful study technique for most students, I excelled in Biology by re-writing notes. Of course, all of this has side-stepped your query about "training out there or books/articles you can recommend". b) Counterintuitively, making diagrams has always worked for me in all subjects. Perhaps the act of making the diagrams for someone who cannot for images is a struggle, and the struggle itself resulted in longer-term learning. So I diagram out everything (including my own lesson plans today) even though I do not think in diagrams.  c)  I think this is the really tough bit ...I never found it hindered academic progress in any subject, but it has affected how i make plans (He may need to plan every step rather than focusing on the final goal). So in other words, allow him to build on details.  Finally (unrelated to your question, but may be relevant in other domains as he goes into higher education), this has affected how I respond to people/ groups (finding it hard to visualize their emotions and reactions). Oddly, this makes people think I work well with others, because I end up not expressing my own emotions because I cannot imagine how they will respond. But helping him deal with visualizing emotions may be the greatest help you can give him

Use sound and hearing? During my BA I found it helpful to read aloud every word, recording and playing it back helped even more. Warning: on a crucial assignment I found I was better informed on the author's words than the lecturer setting the assignment who had overlaid with his own interpretation. I made the mistake of correcting the assumption he had made - not done as an undergraduate.

Everyone is good and bad at different things.  I find that instead of trying to do everything, focus on what I am good at.  I did STEM + Econ in school, and ended up in Engineering.  I'd say that the big thing is that knowing that some types of homework can be a major problem/trigger for a full anphant - for example - Read this and write how it makes you feel.  Describe what you see in your imagination when you read this (the answer is "Nothing, its black, just black, always is")  Draw/paint/color anything abstract  any assignment with feelings, imagination, or emotions/empathy.  If they describe something in pure, simple fact format, like "describe the room", and they say "10m x 15m with white walls", vs someone who says "warm with colorful pictures and a carpet as soft as a kitten" that's fine.  Memory works differently in different people.  You know when someone posts a scary picture on social media or TV, and someone says, "I'll never get that out of my head!" As soon as it is gone, the aphant says "what picture??" I don't remember any. I can't get a disturbing picture _in_ my head. 

Some of the webinars that are linked to on this site are absolutely great.  They give a lot of thoughtful feedback about overlapping symptoms and experiences.  Because the aphantasic experiences seems so varied, I would recommend starting from a place of self-reflection.  It sounds like he's really successful, so getting him to tune in to what specifically helps him have success is a great place to start.  That includes success with which subjects and assignment types, but also in environmental components that help him attend in class and how he can set up his homework space to help him focus.  Once he really has an idea of what works for him, then self-advocacy comes much easier.  It's a fantastic skill even to tell a teacher after class, "hey, I'm having a hard time with this particular unit.  I think it might be my aphantasia.  It's a newer kind of neurodivergence, so there's not a ton of guidance on what helps yet, but if you would be game to work through this unit with me, I'd really appreciate it."  We have to remember that young folks (and plenty of adults too) may not think so much about how brains are different.  It can really empower them to know that the educational system is set up primarily for 1 type of brain and it's ok to ask for something different.

I have personal training. I grew up with it and learned many ways of coping with a visual learning environment. I have been for some myself, but haven't found much, but people tell me how they coped with it.  For me, analogies work best. Physics and mathematics were easy because they don't live in the physical plane. I have also found that everything has core structures that may share similar parts with other fields of existence.  Thank you for what you do, I wish the best of luck to you and your students. Anything I can assist with feel free to message me or email me at [email protected]. 

An excellent question as a teacher of final year International Baccalaureate ( a bit different from your Upper Sixths),  I would love to know the answer myself. But as a self-identified aphant, I would encourage the following a) as for all students, remind this student that exploring his own learning style is worth the time. While so many students now fall for the "I am a visual learner" trap, he should make a very serious attempt to note where/how he learns best in each subject. For example, I learned despite all research indicating that this is not a useful study technique for most students, I excelled in Biology by re-writing notes. Of course, all of this has side-stepped your query about "training out there or books/articles you can recommend". b) Counterintuitively, making diagrams has always worked for me in all subjects. Perhaps the act of making the diagrams for someone who cannot for images is a struggle, and the struggle itself resulted in longer-term learning. So I diagram out everything (including my own lesson plans today) even though I do not think in diagrams.  c)  I think this is the really tough bit ...I never found it hindered academic progress in any subject, but it has affected how i make plans (He may need to plan every step rather than focusing on the final goal). So in other words, allow him to build on details.  Finally (unrelated to your question, but may be relevant in other domains as he goes into higher education), this has affected how I respond to people/ groups (finding it hard to visualize their emotions and reactions). Oddly, this makes people think I work well with others, because I end up not expressing my own emotions because I cannot imagine how they will respond. But helping him deal with visualizing emotions may be the greatest help you can give him