Canals, Cracks and Lakebeds: teacher key

Mars, grade 9 edition, written for 9th grade. In the 1890s Percival Lowell was sure lines on Mars were canals. Read what spacecraft and rovers found instead: a cracked canyon, a lakebed and thin air.

Read the book. Print this page for the key.

Questions and answers

1. Which planet is closer to the Sun, Earth or Mars?
   • They are the same
   • Mars
   • Earth (answer)
2. Ingenuity was built for five test flights. How many more flights than that did it make?
   • 67 (answer)
   • 72
   • 77
3. How was Valles Marineris made?
   • A river carved it
   • The crust stretched and cracked (answer)
   • A lake dried up
4. Why did Curiosity land with the sky crane?
   • The rover was too heavy and big for airbags (answer)
   • The air was too thick
   • Gale Crater was a lake
5. What did Mariner 4 see where canals had been drawn?
   • Rivers
   • None (answer)
   • A lake
6. What does delta mean in this book?
   • A fan of river mud and sand (answer)
   • A kind of storm
   • A rover wheel

Words

• seismometer: quake listener
• lakebed: old lake floor
• canals: dug waterways
• crust: rocky outer layer
• delta: fan of mud