lesson
Seeing needs light entering the eye
1 · Learn
A light source gives out light. Many objects we see do not make their own light; they reflect light from another source. To see such an object, some reflected light must reach our eyes.
In this simple model light travels in straight lines through air until it meets something that changes its path. Draw arrows from the source to the object and then from the object to the eye, not arrows of sight coming out of the eye.
2 · Worked example
A book is visible in a lit room because light from a lamp reflects from the book into my eyes. The book need not glow by itself.
3 · Your turn
Why can the same non-luminous book become difficult to see when the room is dark?
Check your answer
Very little light reaches it and reflects into the eyes. The eyes do not illuminate it with their own beams.
4 · Apply your learning
Draw the source-book-eye path and label the job of each part.
Adult guidance and safety
Never look at the Sun or shine bright lights or lasers into eyes. Use paper diagrams or a dim safe torch pointing away from faces.
Open your writing and drawing pad
Write, draw or show your working. Use a mouse, pen or finger. This pad is not a submitted answer.
Not saved to your account. Download your drawing as PNG and your typed notes as TXT before leaving or refreshing. They are separate files. Do not enter private information.
Open a picture saved on this device to draw on it again. Opening replaces the drawing, but Undo can restore it. PNG only, up to 4 MB and 4096 × 4096 pixels. The picture stays in this browser; it is not uploaded. Paper lines in a saved picture become part of that picture.
Clear the drawing? Your typed notes will stay. You can undo this action.
Your pad is empty.
Open a UTF-8 TXT file from this device, up to 40 KB and 10,000 characters. It stays in this browser. Opening can be undone until you type again. Downloads keep a new copy; they do not change the file you opened.
Replace the notes on this page with the opened file? Download the current notes first if you want to keep them.
Typed notes are not submitted answers.
Check a calculation · Year 5 onward
Use this only when your teacher or adult allows a calculator for the task. Show your thinking first. It does not replace mental or written arithmetic and does not mark your lesson answer.
My observation notebook
With an adult, look at a safe real example or a checked photograph. Name the example and say which you used. Record what you actually notice. Do not taste plants or materials, approach unknown animals or invent missing observations.
Ask your teacher for support with the method and recording. A prediction is what you think might happen; an observation is what you actually see, hear or feel safely.
Keep your notebook: use Download notebook before leaving. Nothing is sent to the website or saved to your account. Reopen the downloaded notebook here to add another day's record. Do not include names, addresses or other private information.
Your records on this page
No observations recorded yet. Look first, then add one.
Reopening adds records; it does not replace your current records. Up to 50 records per notebook. Keep your downloads somewhere private. Editing this notebook does not submit work or complete a lesson.
Practice this lesson
Lesson resources
Browse the available practice activities and worksheets for this lesson.
Your progress