The Orton Gillingham approach is one of the methods we employ in our multi-sensory approach to educational therapy.
This technique was developed in the early-20th century by a neuropsychiatrist and pathologist named Samuel Torrey Orton who worked with and studied children that had language-processing difficulties. He worked together with educator and psychologist Anna Gillingham to create the Orton Gillingham approach to help children with learning differences be able to read, spell and write.
If you would like to learn more about it, you will find detailed information here: https://www.ogtutors.com/aboutog
Even though this approach is most commonly associated with teaching individuals with dyslexia, it is highly effective in teaching any individual struggling with literacy how to overcome their difficulties in reading, writing and spelling. It has even been adapted for math instruction to help students who struggle with arithmetic.