In a rural household’s survey, I am working with Diff.
I have work with dummies for some topics such as el effect of coffee price crisis.
However, I would like to add some qualitative variable as the education level
0. No education
1. Functional illiteracy
2. Complete elementary school
3. High school
4. Higher education.
I think it important to include these levels of education and I am NOT agree to convert them in a 1-0 dummy.

I have been ask to not using regress
What is the best option of model for using?