How much should I help with grade 1 take-home inquiry tasks?

Our son's grade 1 class sends home one small inquiry task a week. This week it was 'find out where the vegetables in our kitchen come from', to share in class with a drawing. We went to the vegetable market together on Saturday, talked to the vendor, and he drew it. I wrote the labels. His teacher's note back said the work should be 'in the child's own voice' and asked parents to step back. I understand the principle, but at six he can't write much on his own. Where do other parents draw the line? Do you write what he says word for word, or let him hand in a drawing with nothing written on it?