"Jullie" and "je" in the same sentence.

I have a sentence, used by a Dutch speaker/instructor:

Vandaag leer ik jullie hoe je vragen kan stellen

In the same sentence, we have the audience referred to as "jullie" and "je". Is this typical? I guess I would expect it to be consistent:

Vandaag leer ik jij hoe je vragen kan stellen

or

Vandaag leer ik jullie hoe jullie vragen kan stellen

Dank je wel !