We got a black, opaque tube and put it on the table with our eye over it. We couldn’t see anything– it was pitch black! This is because the card was opaque and no light could get in to bounce off any objects and into our eyes.
Next, we put different coloured counters in the tube and we still couldn’t see anything! We talked about why we couldn’t see anything and we decided that we needed light. We made a hole in the middle of the tube to let some light into the tube.
We still couldn’t see the counter because light travels in straight lines!ggg