Have a look at the time lapse videos below. The first shows how a beansprout grows over 25 days. The second shows a sunflower growing.
Why do you think the plant grows the root first and the flower last? Think back to what you know about the different parts of a flower to help you answer this question.
Write a paragraph and draw a diagram to answer this question. I have added a link to a BBC Bitesize page about the different parts of plants to help you.