Fill in each blank with the correct word from the lesson.

1. _______ is a form of energy that enables us to see.
2. Light _______ in straight lines — this is called rectilinear propagation.
3. Luminous objects produce their own light through chemical reactions, electrical _______, or nuclear fusion — the sun, candles, tube lights, and glow-worms.
4. _______ objects like glass let most light pass through.
5. _______ objects like frosted glass allow some light through but scatter it.

Choose the best option for each question.

1. What is the speed of light?
   a) 3,000 km/sb) 30,000 km/sc) 300,000 km/sd) 3,000,000 km/s
2. What is the umbra?
   a) The partial shadow regionb) The region of total darkness in a shadowc) Light reflected by the moond) The penumbra's outer edge
3. Why can we see the Moon at night?
   a) The Moon produces its own lightb) The Moon reflects sunlightc) The Moon glows from its interior heatd) Stars illuminate the Moon

Write T for True or F for False in the brackets.

1. 300,000 km/s is one of the key concepts in the lesson on How Light Travels.
2. 3,000 km/s is the main topic of this lesson.
3. The region of total darkness in a shadow is one of the key concepts in the lesson on How Light Travels.
4. The partial shadow region is the main topic of this lesson.

1. In your own words, explain what How Light Travels means.
2. List two things you learned from this lesson on How Light Travels.