What courses did Gryffindor, Ravenclaw, Hufflepuff and Slytherin teach in early Hogwarts?

We are not sure, but my head is like this: It is said that helga hufflepuff is very talented in cooking and food-related curses, so Professor Hufflepuff teaches curses, cooking classes and baking classes.

Because salazar slytherin was a snake man who successfully tamed the basilisk, he taught a lesson about magical animals and magical creatures. Because he has the gift of mindfulness, I think he also taught a duel class, teaching students to use mindfulness to predict the next spell they might need to block. Since he secretly built the Chamber of Secrets (and possibly other parts of the castle), I believe he also taught a course on magical structure.

In this era of mass illiteracy, rowena ravenclaw may have taught literacy (reading and writing) as a way to store, transmit and accept accumulated knowledge. She also teaches herbalism, potions and astrology.

Godric Gryffindor is a gifted soldier. He teaches dueling lessons with Professor Slytherin. He also taught Muggles to fight with swords, and the goblin made a terrible sword for him. In this era, wizards and witches may need to protect themselves without revealing their magical abilities. He may also have taught Muggle English navigation courses with Professor Hufflepuff, because both courses support tolerance and harmony between different races. Suppose he also teaches deformation classes in his spare time, just because someone needs to start teaching Gryffindor's long and glorious tradition. :)

It is very likely that no matter which class the first class is assigned to, he will learn all the subjects/topics from that professor/founder, and he can also learn from another founder/professor unless he gets special permission.

According to the clues we have, these are my best guesses

All the pictures belong to Wizarding World Company. Rowena ravenclaw values knowledge. She is famous for her creativity and wisdom. According to legend, Rowena had a dream that a dog with warts was taken to a cliff by the lake. This dream prompted Rowena and her friends to build Hogwarts in that place.

She must have taught divination, because Rowena is a prophet. Study the magical properties of numbers, including predicting the future with numbers and numerology. Astronomy-her impeccable knowledge must also extend to planets and stars. Salazar slytherin values ambition and is famous for his concentration and his ability to speak paston.

His major must be pharmacy. Generally speaking, Slytherin students have the ability to make medicines, and salazar must be a professional pharmacist. A study of ancient runes. He seems to be the most likely person to be interested in ancient classics. Wand Learning-salazar made his own wands and was good at making them.

Helga hufflepuff values diligence and kindness more than anything else. She is proficient in magic and food-related magic.

Her major must be very attractive. Herbology. The element of Hufflepuff is soil, so Hrga is naturally good at growing plants. Protect magical creatures. If her kindness extends to animals, it is not surprising. She must have made a lot of efforts to make the magic world more sympathetic to them.

Some common subjects, these four people must have taught the alchemy of transforming ghosts. I don't think there were muggle learning courses at that time, because even in Harry's time, the wizard world was medieval.

The pipeline system began to be used in18th century, while Muggles built the first toilet with flushing system in16th century.