The home education law doesn’t define a day, so use a standard that you feel comfortable with.
I recommend doing some research and some thinking before you decide.
Personally, I don’t think a 5-year-old child should spend more than 30 minutes a day doing seat-work. Even then, I would break the day into 10-20 minute sessions.
At that age, my own children worked 30 to 60 minutes a day in 10 to 15-minute sessions. We started with 5-minute sessions and worked our way up to 10 or 15 minutes. Even an older child may not benefit from focusing longer than 20 minutes at a time before taking a short break.
Each year, add 30 minutes a day:
- 5 years old: 30 minutes maximum
- 6 years old: 1 hour maximum
- 7 years old: 1 ½ hours maximum
- 8 years old: 2 hours maximum
- 9 years old: 2 ½ hours maximum
- 10 years old: 3 hours maximum
- 11 years old: 3 ½ hours maximum
- 12 years old: 4 hours maximum
- 13 years old and older: 4 ½ hours maximum