Are you smarter than a 5th grader?

Answer key

1. 1. The denominators are equal, so add the numerators: four fourths make one whole.
2. 96. Split 12 × 8 into 10 × 8 and 2 × 8. Adding 80 and 16 gives 96, a useful way to check multiplication mentally.
3. 12. Division undoes multiplication. Because 12 × 12 = 144, dividing 144 into twelve equal groups puts twelve in each group.
4. 40 square centimeters. Area is length times width: 8 × 5 = 40 square centimeters.
5. 24 inches. Perimeter measures the boundary. Four sides of 6 inches total 24 inches.
6. 700. Reading from right to left gives ones, tens, hundreds, then thousands. The 7 occupies the hundreds place, so it contributes 700.
7. 0.5. One-half equals five-tenths: 1 ÷ 2 = 0.5. The decimal 0.05 is five-hundredths, which is ten times smaller.
8. 90. A full turn is 360 degrees, and a right angle is one-quarter of that turn. Four right angles fit around a point.
9. 13. Thirteen can be divided evenly only by 1 and 13. The other choices are divisible by 3, so they are composite rather than prime.
10. $2.50. Line up the decimal points and subtract 10.00 − 7.50 = 2.50. Check by adding the price and change back to $10.
11. Photosynthesis. In photosynthesis, plants use light energy to help make sugars from carbon dioxide and water.
12. Heart. The heart moves blood by contracting. Lungs exchange gases, while the heart supplies the pumping force that circulates the blood.
13. Gravity. Gravity is an attractive force between masses. Earth’s mass makes it the main source of the pull on a ball near its surface.
14. Evaporation. During evaporation, liquid water becomes water vapor. This can happen below boiling temperature, as when a puddle slowly dries.
15. Condensation. Water vapor in the surrounding air cools and becomes liquid on the glass. The droplets come from the air, rather than passing through the glass.
16. Roots. Roots absorb water and minerals from soil, and stems transport them. Leaves usually do most of the plant’s photosynthesis.
17. Dolphin. Dolphins are mammals: they breathe air with lungs and feed their young milk. Living in water does not make a dolphin a fish.
18. Earth rotating on its axis. Earth rotates, bringing different parts of its surface into sunlight and then darkness.
19. Copper. Copper lets electric charge move readily, so it is used inside many wires. Rubber and plastic coverings help insulate those conducting wires.
20. A producer. A producer makes food using an energy source such as sunlight. A consumer obtains food by eating other organisms instead.
21. Washington, DC. Washington, DC, is the federal capital. It is a district rather than a US state.
22. Pacific Ocean. The Pacific borders the western coasts of California, Oregon, and Washington.
23. Canada. Canada borders the northern edge of the contiguous states. Contiguous means the connected group of 48, excluding Alaska and Hawaii.
24. Mexico. Mexico lies across Texas’s international border. Much of that boundary follows the Rio Grande, rather than a straight line.
25. Legend or key. A map key explains symbols, such as a line for a road or a dot for a city. The scale instead relates map distance to real distance.
26. Equator. The Equator is zero degrees latitude. The Prime Meridian is zero degrees longitude, a different reference line running between the poles.
27. North America. The contiguous states and Alaska are in North America. Hawaii is in the central Pacific and is geographically part of Polynesia.
28. East. East and west lie 180 degrees apart on a compass. North and south form the other pair of opposite cardinal directions.
29. Hawaii. Hawaii consists of islands in the central Pacific. Alaska is separate from the contiguous states too, but is attached to the North American mainland.
30. Appalachian Mountains. The Appalachians run through eastern North America. The Sierra Nevada is in the western United States, while the Andes are in South America.
31. Dog. Dog names the animal and is the noun. Barked describes the action and is the verb; the is an article.
32. Quickly. Quickly tells how the action happened, so it modifies closed. Adverbs can describe verbs; adjectives instead commonly describe nouns.
33. Stingy. Stingy means unwilling to give or share. Giving, kind, and helpful are closer to generous, so they do not express its opposite.
34. Huge. Huge and enormous both mean very large. Tiny expresses the opposite size, while quiet and narrow describe different qualities.
35. Their backpacks are blue.. Their shows possession. They’re means they are, and there commonly names a place or introduces a sentence such as There is a book.
36. Children. Child has the irregular plural children. It does not follow the usual pattern of simply adding -s, as in book and books.
37. Question mark. A question mark ends a direct question such as “Where are we?”
38. The birds built a nest.. The birds is the subject, and built is the verb. The other choices are fragments that do not express a complete independent statement.
39. Unhappy. Adding un- to happy reverses its meaning. Happiness uses a suffix at the end to turn the adjective into a noun.
40. Wrote. Use wrote for a completed past action: I wrote yesterday. Use written with a helping verb, as in I have written.
41. George Washington. Washington served from 1789 to 1797. The wording under the Constitution distinguishes this office from earlier presiding roles in the Continental Congress.
42. 1776. The Continental Congress adopted the Declaration on July 4, 1776. The Constitution was drafted later, in 1787, and serves a different purpose.
43. 13. Thirteen colonies declared independence. The number of states later grew, which is why the flag combines thirteen stripes with fifty stars.
44. Legislative. Congress is the legislative branch and passes federal legislation. The President heads the executive branch, while courts form the judicial branch.
45. Senate and House of Representatives. Congress has two chambers. States receive two Senate seats each, while House seats are apportioned among states by population.
46. 2. Every state has two senators, giving states equal representation in the Senate. Representation in the House follows a different, population-based system.
47. The US Constitution. The Preamble introduces the Constitution’s purposes. The Declaration of Independence is an earlier document announcing separation from Britain.
48. The original thirteen colonies. The thirteen stripes recall the original colonies. The fifty stars represent the states, so the two parts of the design commemorate different counts.
49. Judicial. The Supreme Court belongs to the judicial branch and decides cases. Congress makes up the legislative branch, and the President heads the executive branch.
50. A change or addition to the Constitution. An amendment changes or adds to the Constitution. It requires the constitutional proposal and ratification process rather than an ordinary presidential announcement.