Photographs can be such a strong tool in getting kids to write. Emergent writers need the kinesthetic/hands on experience before they move to the abstract and a picture can give this to them. One activity you can do to help your child to write is to have them pick a picture that is important to them. Ask them to tell you who is in the picture, when it took place, what they were feeling and where it was. After they tell you the details out loud, help them write them down.
In the classroom, I often take pictures of kids while they are playing and use these as a writing prompt. If they are building towers, making up stories with stuffies or building innovative machines it is great to record this and have them write about it. They can write the steps as to how they built their creation, if they gave it a name and what it does. If they are building a story with puppets or stuffies they can tell you what is going on in the story.
Following a child's interest is the most engaging way to extend on their learning. Here I have posted some every day activities that can draw from various strands across different age groups. Remember each child has different interests so the key to working with your child is to follow their lead and ask the right questions.