Once children can write a sentence, they then need to learn how to structure a paragraph. Before this, scaffold their learning by creating their paragraph structure for them.
In Write in Colour - I suggest paragraph writing should begin when sentences become easy. This is often late primary. When sentences start to roll with more fluency and ease, put more effort into learning paragraph structure. Write in Colour Level 2 teaches paragraph structure.
This is so important because it helps them to see their writing as part of a bigger picture. When my 10 year old tells me 2-3 sentences per day and I type for her, over a week we write a paragraph. Over 3 weeks we write 3 paragraphs - she talks, I type. At the end of 3 weeks we have an excellent 3 paragraph essay!
We might only do this 3 times per year. It's ok. By the time she's in Yr 9, we may have written 15 essays together. But every one of them is excellent. And they are all available for her to go back and read in her Lapbook.
She feels confident about her ability to write an essay. She sees herself as a good writer. She has a positive attitude to develop her skill.