Book 21 science quiz: free printable worksheet

Fill in the missing number

Number bank: 10   11   32   45   100   250   900   1,400   1931   1975   2008   780,000

1. Physicist Paul Dirac showed in _______ that single magnetic poles could exist in theory, but nobody has found one.
   From: Can a Magnet Have Only One Pole?
2. The outer core is about _______ miles thick.
   From: How Does Swirling Liquid Metal Deep Inside Earth Make a Magnet?
3. The last full flip happened about _______ years ago.
   From: Did the North and South Magnetic Poles Ever Swap Places?
4. Jupiter spins once every _______ hours.
   From: Why Does Jupiter Have Such a Huge Magnetic Field?
5. About every _______ years, the Sun’s field flips its north and south poles.
   From: Why Do Scientists Call the Sun a Giant Magnet?
6. On the ground, it is about _______ times weaker than the field at the surface of a typical fridge magnet.
   From: Is Earth’s Magnet Stronger than a Fridge Magnet?
7. Around _______ years ago, sailors in China began using magnetized needles on ships, and the idea soon spread to other parts of the world.
   From: How Did People First Discover the Compass?
8. Pairs like NE mean halfway between, and northeast is _______ degrees.
   From: What Do the Letters and Numbers on a Compass Mean?
9. Old sea charts had large, colorful roses with many points, often _______.
   From: What Is a Compass Rose on a Map?
10. Some maglev trains in service reach over _______ miles per hour.
    From: How Can a Train Float on Magnets?
11. In _______, scientists studied thousands of satellite pictures and reported that grazing cattle and resting deer tended to line up north and south.
    From: Do Cows and Deer Really Face North and South?
12. A scientist discovered these bacteria in _______ while looking at mud under a microscope.
    From: Which Tiny Living Things Carry Their Own Compass Needles?