Looking for a website/dictionary to give students the Word Classes/Families of words

I've been trying to find a website or dictionary that gives students the word classes/families. I haven't been able to find one. Most dictionaries would give suggestions of other related words. Some are part of the word family of the word you're viewing, some are not.

When I teach my students about finding out the word families, they can't do it because they don't have a place to go to. I always have to tell them the word families.

Do you have any idea where I can find such a website or resource?

By Word Families, I mean if my student is studying "participate" (V), I also want them to find out the other word family members - "Participation" , "participative", etc.

I'm afraid that online dictionaries that I know don't do that thoroughly.