Shall somebody know how to learn harmonie basics to a child ?

Hi everybody !

I'm a proud father of a little 5 years old girl.

We are learning theory, she knows how to read music ( French Dandelot method for notes ). We begun with the Russian school of piano playing, twice a day ( 5 minutes ).

I'd like to help her manipulating easy chords in order for her to improvise. Would you have methods, ways to help us ?