Corrected version for a 7-year-old:
Vision is our ability to see. Light enters your eye through the pupil (the dark hole in the iris) and then passes through the lens. The back of the eye (the retina) gets the picture upside down. Nerves send the picture to the brain, and the brain turns it the right way up.
Simple step-by-step:
- Light bounces off things and goes into your eye through the pupil.
- The lens helps focus the light so the picture is sharp.
- The retina at the back of the eye gets the picture upside down.
- Nerves carry the picture from the retina to the brain.
- The brain flips the picture the right way up so you can understand what you see.
Grammar notes (short):
- I added a mention of the pupil because the iris is around it and saying "through the pupil" is clearer.
- I split a long run-on sentence into two sentences so the meaning is clearer.
- I used simple words and short sentences to make it easy for a 7-year-old to read.