Overview

Lesson Procedure

55-65 minutes of class time across 5 phases.

1. Warm-Up5-10 minutes
2. Direct Instruction15 minutes
3. Guided Practice15 minutes
4. Independent Practice15-20 minutes
5. Closure5 minutes

1. Warm-Up5-10 minutes

   Project the three sentences from an invented school library report. Give pairs two minutes.

   Warm-Up Prompt

   Sentence A: "Students checked out 312 books in September." Sentence B: "September checkouts were twice those of August, so the new display by the door is probably drawing readers in." Sentence C: "Someday the library may not need paper books at all." Which sentence could you check in the records? Which is a conclusion drawn from the records? Which goes beyond anything the records show?

   Take answers. A is a fact: anyone can check it in the checkout records. B is a reasoned judgment: it draws a conclusion from findings (the two months' counts) and shows its reasoning ("so"). C is speculation: nothing in the records can show it. Tell students that RST.6-8.8 asks them to distinguish these three kinds of statements in science and technical texts, where they often sit side by side in the same paragraph.

2. Direct Instruction15 minutes

   Part 1: Three kinds of statements. Keep this table and Diagram 1 up for the whole lesson.

   Facts, reasoned judgments and speculation

   Kind of statement	What it is	A question to ask
   Fact	A statement of something observed or measured, which other people could check	How could someone check this?
   Research finding	A result that a scientist observed or measured in an investigation; a finding is a kind of fact	Who found it, and how?
   Reasoned judgment based on research findings	A conclusion drawn from research findings, with the reasoning shown	What findings is it based on, and does the reasoning follow?
   Speculation	A statement that goes beyond the evidence: a guess, a possibility or a prediction	Could any evidence the author has actually show this?
   Hypothesis	A possible explanation that can be tested; before it is tested, it is a kind of speculation	What test could settle it?

   Part 2: Model with Passages 1 and 2. Percival Lowell (1855-1916) built an observatory in Flagstaff, Arizona, to study Mars. In Passage 1 he reports what careful telescope work had measured. In Passage 2, the opening of his last chapter, he states his conclusion about the canals. Words to know for Passage 1: areographic features (markings on Mars; "areo-" means Mars), traverse of the disk (trip across the planet's round face in a telescope), nicety (exactness), axis (the line a planet spins around), tilt of the equator to the plane of the orbit (how far the planet leans), similitude and parallelism (likeness), Nautical Almanac (a yearly book of sky data), terrestrial (Earth's), ellipticity (how stretched the oval of the orbit is). For Passage 2: beings (living creatures), atomic theory (the idea that matter is made of atoms), predicate (state), cosmopolitan (worldwide), girdling (circling), entity (a single thing), posits (assumes), community of interest (shared goals), enterprises (projects).

   1Attention shows these areographic features to be on hand with punctual precision for their traverse of the disk once every twenty-four hours and thirty-seven minutes. For over two hundred years this has been the case, their untiring revolutions having been watched so well that we know the time they take to the nicety of a couple of hundredths of a second. We thus become possessed of a knowledge of the length of the Martian day and it is not a little interesting to find that it very closely counterparts in duration our own, being only one thirty-fifth the longer of the two. We also find from the course the markings pursue the axis about which they turn; and just as the period of the rotation tells us the length of the Martian day so the tilt of the axis, taken in connection with the form of the orbit, determines the character of the Martian seasons. Here again we confront a curious resemblance in the circumstances of the two planets, for the tilt of the equator to the plane of the orbit is with Mars almost precisely what it is for the Earth. The more carefully the two are measured the closer the similitude becomes. Sir William Herschel made the Martian 28°, Schiaparelli reduced this to 25°, and later determination by the writer puts it nearer 24°. The latter is the one now adopted in the British Nautical Almanac for observers of the planet. This is a very close parallelism indeed; so that in general character the Martian seasons are nearly the counterpart of ours. In length, however, they differ; first because the year of Mars is almost double the length of the terrestrial one and secondly because from the greater ellipticity of Mars’ orbit the seasons are more unequal than is the case with us, some being run through with great haste, others being lingered on a disproportionate time. [...] On this division our seasons in the northern hemisphere last respectively: spring, 91 days; summer, 92 days; autumn, 92 days; and winter, 90 days. On Mars these become, reckoned in our days: spring, 199 days; summer 183 days; autumn, 147 days; and winter, 158 days. If we had counted them in Martian days they would have totaled about one thirty-fifth less in number each.

   1That Mars is inhabited by beings of some sort or other we may consider as certain as it is uncertain what those beings may be. The theory of the existence of intelligent life on Mars may be likened to the atomic theory in chemistry in that in both we are led to the belief in units which we are alike unable to define. Both theories explain the facts in their respective fields and are the only theories that do, while as to what an atom may resemble we know as little as what a Martian may be like. But the behavior of chemic compounds points to the existence of atoms too small for us to see, and in the same way the aspect and behavior of the Martian markings implies the action of agents too far away to be made out.

   2But though in neither case can we tell anything of the Bodily form of its unit, we can in both predicate a good deal about their workings. Apart from the general fact of intelligence implied by the geometric character of their constructions, is the evidence as to its degree afforded by the cosmopolitan extent of the action. Girdling their globe and stretching from pole, to pole, the Martian canal system not only embraces their whole world, but is an organized entity. Each canal joins another, which in turn connects with a third, and so on over the entire surface of the planet. This continuity of construction posits a community of interest. Now, when we consider that though not so large as the Earth the world of Mars is one of 4200 miles diameter and therefore containing something like 212,000,000 of square miles, the unity of the process acquires considerable significance. The supposed vast enterprises of the earth look small beside it. None of them but become local in comparison, gigantic as they seem to us to be.

   • A fact, and how to check it

     Passage 1. Lowell reports that the markings cross the disk "once every twenty-four hours and thirty-seven minutes." What kind of statement is this, and how could it be checked?

     Result: A fact. It reports a measurement that other observers can repeat, and Lowell says it has been "watched so well" for "over two hundred years" that it is known "to the nicety of a couple of hundredths of a second." Modern measurements give 24 hours 37 minutes 22.7 seconds. Even his "one thirty-fifth the longer" can be checked: compared with the 23 hours 56 minutes that Earth takes to spin once, Mars takes 41 minutes more, and 41 ÷ 1,436 minutes is about 1/35.

   • A reasoned judgment based on research findings

     Passage 1. Lowell writes that "in general character the Martian seasons are nearly the counterpart of ours." What is this statement based on, and what kind is it?

     Result: A reasoned judgment. The finding is the measured tilt: "later determination by the writer puts it nearer 24°," close to Earth's tilt of about 23.5°. The reasoning is given: the tilt "determines the character of the Martian seasons," so a similar tilt means similar kinds of seasons. Lowell himself limits the judgment: "In length, however, they differ," and Diagram 2 shows by how much.

   • A statement of fact can fail its check

     Passage 2, paragraph 2. Lowell writes that Mars is "one of 4200 miles diameter and therefore containing something like 212,000,000 of square miles." Are these facts, and are they right?

     Result: Both are statements of fact, because both can be checked. The diameter is close to the modern value of about 4,212 miles. The area is not: the surface of a ball 4,200 miles across is π × 4,200² square miles, about 55,400,000, and modern measurements give about 55,900,000. Lowell's figure is almost four times too large. A statement is a fact-type statement because it can be checked, not because it is true.

   • Speculation stated as certainty

     Passage 2, paragraph 1: "That Mars is inhabited by beings of some sort or other we may consider as certain as it is uncertain what those beings may be." Fact, reasoned judgment or speculation?

     Result: Speculation, even though Lowell calls it "certain." No one had seen any beings; Lowell admits "we know as little as what a Martian may be like." His support is a comparison with atoms and the "geometric character" of lines that he takes to be "constructions." A conclusion about things no evidence could show goes beyond the evidence. Diagram 1's note applies: confident words do not decide the category.

3. Guided Practice15 minutes

   Pairs read Passage 3, from Wallace's reply. Wallace (1823-1913) was a British naturalist who worked out the theory of evolution by natural selection at the same time as Charles Darwin. Here he reports what astronomers found when they looked for water vapour on Mars with a spectroscope (an instrument that spreads light into its colors; a gas such as water vapour leaves dark lines in the colors). Words to know: Sir William Huggins (a British astronomer), aqueous vapour (water vapor), ascertained (found out), negative (finding nothing), Lick Observatory (in California), Marchand, Slipher (astronomers), Pic du Midi (a mountain observatory in France), accordant (in agreement), molecular theory of gases (the science of how gas particles move; Wallace means a calculation that a small planet's gravity cannot hold on to water vapor), presumably (probably), delicacy (difficulty, needing great care), conjecture (guess), omnipresent (everywhere). Pairs mark each sentence F, RJ or S, using three highlighter colors.

   1As Sir William Huggins is the chief authority quoted for this fact, and is referred to as being almost conclusive in the third edition of Miss Clerke's History of Astronomy in 1893, I have ascertained that his opinion at the present time is that "there is no conclusive proof of the presence of aqueous vapour in the atmosphere of Mars, and that observations at the Lick Observatory (in 1895), where the conditions and instruments are of the highest order, were negative." He also informs me that Marchand at the Pic du Midi Observatory was unable to obtain lines of aqueous vapour in the spectrum of Mars; and that in 1905, Slipher, at Mr. Lowell's observatory, was unable to detect any indications of aqueous vapour in the spectrum of Mars.

   2It thus appears that spectroscopic observations are quite accordant with the calculations founded on the molecular theory of gases as to the absence of aqueous vapour, and therefore presumably of liquid water, from Mars. It is true that the spectroscopic argument is purely negative, and this may be due to the extreme delicacy of the observations required; but that dependent on the inability of the force of gravity to retain it is positive scientific evidence against its presence, and, till shown to be erroneous, must be held to be conclusive.

   3This absence of water is of itself conclusive against the existence of animal life, unless we enter the regions of pure conjecture as to the possibility of some other liquid being able to take its place, and that liquid being as omnipresent there as water is here. [...]

   • An author who sorts his own evidence

     Passage 3. Pairs find the research findings, the reasoned judgment Wallace draws from them, and the statement he himself calls speculation.

     Result: Findings (facts): observations at the Lick Observatory in 1895 "were negative," Marchand "was unable to obtain lines of aqueous vapour," and Slipher in 1905 "was unable to detect any indications" of it. Reasoned judgment: these agree with the gravity calculation "as to the absence of aqueous vapour, and therefore presumably of liquid water, from Mars." Wallace also weighs the evidence: the spectroscope result is "purely negative" (the lines may simply be too faint to see), while the gravity calculation is "positive scientific evidence." Speculation: another liquid taking water's place, which he calls "the regions of pure conjecture."

   Debrief: Wallace says the gravity argument "must be held to be conclusive" only "till shown to be erroneous." What does that phrase tell you about reasoned judgments? (They are the best conclusion from the findings so far, and new findings can change them. Passage 6 and the homework come back to this.) Then start Activities 1-3.

4. Independent Practice15-20 minutes

   Students read Passages 4 and 5 on their own and answer quiz questions 1-20. Passage 4 is Wallace's argument about the temperature of Mars. Words to know: atmospheric envelope (the layer of air around a planet), density (how much air is packed into a space), altitude (height above sea level), grappled with (dealt with), plateaux (high, flat lands), Quito (the capital of Ecuador, high in the Andes Mountains, near the equator), Manaos (Manaus, a city in Brazil near sea level on the Amazon River), Humboldt (Alexander von Humboldt, a German scientist who measured temperatures on mountains), [17] (Wallace's footnote, printed as the next paragraph), barometer (an instrument that measures air pressure; "a four inches barometer" means air pushing a column of mercury only 4 inches high, where at sea level on Earth it is about 30 inches), enquirers (researchers), to-31° F. (to -31 °F; the missing space is in the original). Passage 5 is a modern article written for this page. Words to know: orbiter (a spacecraft that circles a planet), rover (a robot vehicle that drives on a planet), crater (a bowl-shaped hole made by a space rock), delta (land built up where a river flows into a lake or sea), microbes (living things too small to see without a microscope).

   1Recurring now to the question of climate, which is all-important, Mr. Lowell never even discusses the essential point--the temperature that must necessarily result from an atmospheric envelope one-twelfth (or at most one-seventh) the density of our own; in either case corresponding to an altitude far greater than that of our highest mountains.[17] Surely this phenomenon, everywhere manifested on the earth even under the equator, of a regular decrease of temperature with altitude, the only cause of which is a less dense atmosphere, should have been fairly grappled with, and some attempt made to show why it should not apply to Mars, except the weak remark that on a level surface it will not have the same effect as on exposed mountain heights. But it does have the same effect, or very nearly so, on our lofty plateaux often hundreds of miles in extent, in proportion to their altitude. Quito, at 9350 ft. above the sea, has a mean temperature of about 57° F., giving a lowering of 23° from that of Manaos at the mouth of the Rio Negro. This is about a degree for each 400 feet, while the general fall for isolated mountains is about one degree in 340 feet according to Humboldt, who notes the above difference between the rate of cooling for altitude of the plains--or more usually sheltered valleys in which the towns are situated--and the exposed mountain sides. It will be seen that this lower rate would bring the temperature of Mars at the equator down to 20° F. below the freezing point of water from this cause alone.

   2[Footnote 17: A four inches barometer is equivalent to a height of 40,000 feet above sea-level with us.]

   3But all enquirers have admitted, that if conditions as to atmosphere were the same as on the earth, its greater distance from the sun would reduce the temperature to-31° F., equal to 63° below the freezing point. It is therefore certain that the combined effect of both causes must bring the temperature of Mars down to at least 70° or 80°below the freezing point.

   1Since 1965, spacecraft have photographed Mars up close. Mariner 4 flew past the planet that year, and Mariner 9 began mapping it from orbit in 1971. Their pictures showed craters, huge volcanoes and deep canyons, but none of the long, straight canals that Percival Lowell had drawn. Scientists today explain the canals as an illusion: when an observer strains to see details at the limit of a telescope, the eye tends to join faint, scattered spots into lines.

   2Rovers and orbiters have measured the planet directly. The air pressure at the surface is less than 1 percent of the air pressure on Earth, and the air is about 95 percent carbon dioxide. The average temperature is about -80 °F (about -62 °C). Liquid water cannot last long on the surface today: in air that thin, it quickly boils away or freezes. The air does hold a small amount of water vapor, and the polar caps contain a great deal of water ice.

   3The rocks tell a different story about the past. In Gale Crater, the rover Curiosity found layers of fine mudstone, a rock that forms when mud settles slowly to the bottom of still water. From these layers, scientists have concluded that a lake filled the crater, on and off, for millions of years, more than 3 billion years ago. The rover Perseverance, which landed in Jezero Crater in 2021, is studying what was once a river delta, and it has collected rock samples.

   4Could anything have lived in those lakes? No one knows. Some scientists think tiny microbes might once have lived there, and a few suggest that microbes could survive even today, deep underground, where it is warmer and water might stay liquid. No life has been found on Mars, and no experiment has yet shown that it ever existed. Samples brought back to Earth might one day help answer the question.

5. Closure5 minutes

   Exit ticket: "Write one fact, one reasoned judgment and one speculation from today's passages. Beside each, write the question from Diagram 1 that told you which kind it is." Sort the tickets into "all three correct with reasons," "correct kinds but no reasons" and "confuses reasoned judgment with speculation."

   Teacher note on the science. Passage 5 gives the modern picture of Mars and should be read alongside the older texts. Some of Lowell's measurements hold up well: the length of the Martian day is 24 hours 37 minutes 22.7 seconds, and his season lengths match modern values within about a day. His tilt of "nearer 24°" is a little low (the modern value is about 25.2°, closer to Schiaparelli's 25°), and his 212,000,000 square miles is almost four times the true area of about 55,900,000. Wallace's conclusion that Mars is far too cold for animal life has held up, but parts of his reasoning have not, as students will see when they compare Passages 4 and 6 with Passage 5. The passages keep the words and spelling of the 1906 and 1907 editions ("vapour," "plateaux").

   Homework passage. Passage 6 is the end of Wallace's book, where he sums up his case. Words to know: alpine (of high mountains), afford (give), Dr. Johnstone Stoney (George Johnstone Stoney, an Irish physicist who calculated which gases a planet's gravity can hold), controvert (argue against), scantiness (small amount), Langley (Samuel Langley, an American scientist who measured the heat given off by the moon), incompatible (not able to exist together), organic life (living things), in the multiple ratio of their respective weights (each adding to the strength of the others), postulates (assumes), uninhabitable (not able to support life).

   1[...] These two independent arguments--from alpine temperatures and from those of the moon--support and enforce each other, and afford a conclusive proof (as against anything advanced by Mr. Lowell) that the temperature of Mars must be far too low to support animal life.

   2A third independent argument leading to the same result is Dr. Johnstone Stoney's proof that aqueous vapour cannot exist on Mars; and this fact Mr. Lowell does not attempt to controvert.

   3To put the whole case in the fewest possible words:

   4All physicists are agreed that, owing to the distance of Mars from the sun, it would have a mean temperature of about-35° F. [...] even if it had an atmosphere as dense as ours.

   5(2) But the very low temperatures on the earth under the equator, at a height where the barometer stands at about three times as high as on Mars, proves, that from scantiness of atmosphere alone Mars cannot possibly have a temperature as high as the freezing point of water; and this proof is supported by Langley's determination of the low maximum temperature of the full moon.

   6The combination of these two results must bring down the temperature of Mars to a degree wholly incompatible with the existence of animal life.

   7(3) The quite independent proof that water-vapour cannot exist on Mars, and that therefore, the first essential of organic life--water--is non-existent.

   8The conclusion from these three independent proofs, which enforce each other in the multiple ratio of their respective weights, is therefore irresistible--that animal life, especially in its higher forms, cannot exist on the planet.

   9Mars, therefore, is not only uninhabited by intelligent beings such as Mr. Lowell postulates, but is absolutely UNINHABITABLE.

Differentiation Strategies

Assessment Guidance

1. Question 1 of 20 · Multiple Choice

   Passage 4, paragraph 1: "Quito, at 9350 ft. above the sea, has a mean temperature of about 57° F." What kind of statement is this?

   AA reasoned judgment, because Wallace uses it later in his argument about Mars BSpeculation, because no one could measure a whole city's temperature CA fact: it reports a measured height and temperature that others can check DA reasoned judgment, because the word "about" shows that Wallace is not sure

2. Question 2 of 20 · Multiple Choice

   Use Diagram 1. Which sentence from Passage 4 gets a "yes" at question 1 of the flowchart?

   A"the general fall for isolated mountains is about one degree in 340 feet according to Humboldt" B"a regular decrease of temperature with altitude, the only cause of which is a less dense atmosphere" C"Surely this phenomenon, everywhere manifested on the earth even under the equator, ... should have been fairly grappled with" D"in either case corresponding to an altitude far greater than that of our highest mountains"

3. Question 3 of 20 · Multiple Choice

   Wallace says Quito's 23° drop in temperature is "about a degree for each 400 feet." Which calculation shows that this follows from his numbers?

   A9,350 ÷ 57 is about 164 feet for each degree B9,350 ÷ 23 is about 407 feet for each degree C57 - 23 = 34 degrees for the height of Quito D9,350 ÷ 340 is about 27.5 degrees for the height of Quito

4. Question 4 of 20 · Multiple Choice

   Passage 4, paragraph 1 ends: "this lower rate would bring the temperature of Mars at the equator down to 20° F. below the freezing point of water from this cause alone." What kind of statement is this?

   AA fact, because Wallace gives an exact number of degrees for the equator of Mars BSpeculation, because no one in 1907 could have any evidence about Mars CA fact, because the number comes straight from Humboldt's measurements on mountains DA reasoned judgment: it applies cooling measured on Earth to the thin air of Mars

5. Question 5 of 20 · Multiple Choice

   Why does Wallace include footnote [17], "A four inches barometer is equivalent to a height of 40,000 feet above sea-level with us"?

   ATo show that the barometers used for Mars were broken and gave readings that were far too low BTo link Mars's thin air to a great height on Earth, where cooling has been measured CTo prove that Mars has mountains 40,000 feet high standing near its equator DTo give his own guess about the air of Mars, since no measurements existed

6. Question 6 of 20 · Short Answer

   Passage 4, paragraph 3 says that with an atmosphere like Earth's, Mars would reach "-31° F., equal to 63° below the freezing point." Show that -31° F is 63° below freezing, and explain whether the -31° F is a fact, a reasoned judgment or speculation.

   Show model answer

7. Question 7 of 20 · Multiple Choice

   Passage 4 ends: "It is therefore certain that the combined effect of both causes must bring the temperature of Mars down to at least 70° or 80°below the freezing point." What kind of statement is this?

   AA reasoned judgment: a conclusion from two research-based estimates, not a measurement BA fact, because Wallace says it is "certain" and uses the word "must" CSpeculation, because the two causes are only guesses that no one had any evidence for DA fact, because it gives a range of temperatures, 70° or 80°, as a measurement would

8. Question 8 of 20 · Short Answer

   Passage 4 begins: "Mr. Lowell never even discusses the essential point." Is this sentence about Lowell's book a fact, a reasoned judgment or speculation? Explain how a reader could check it, and whether checking could prove it wrong.

   Show model answer

9. Question 9 of 20 · Short Answer

   Wallace's conclusion in Passage 4 rests on two causes that lower the temperature of Mars. Name both causes, and for each one name the research finding he uses.

   Show model answer

10. Question 10 of 20 · Multiple Choice

    Passage 5, paragraph 1: "Mariner 4 flew past the planet that year, and Mariner 9 began mapping it from orbit in 1971." Why is this a fact and not speculation?

    ABecause it appears in a modern article, and modern articles contain only facts BBecause it names two spacecraft, and anything written about spacecraft is a fact CBecause scientists today agree with it, and agreement among scientists makes a statement a fact DBecause it reports events with dates that anyone can check in the records of the missions

11. Question 11 of 20 · Multiple Choice

    Passage 5, paragraph 1: "Scientists today explain the canals as an illusion." What kind of statement is this?

    AA fact, because it is printed in a modern science article BSpeculation, because no one can know what Lowell's eyes really saw CA reasoned judgment, based on the photographs and on how the eye joins faint spots DA fact, because Lowell himself later admitted in his book that the canals were an illusion

12. Question 12 of 20 · Multiple Choice

    Passage 5, paragraph 3 says that "scientists have concluded that a lake filled the crater, on and off, for millions of years." What kind of statement is this, and what is it based on?

    AA reasoned judgment, based on layers of mudstone, a rock that forms in still water BA fact, based on photographs that the rover took of the lake filled with water CSpeculation, based on a guess that the crater once had living things in it DA reasoned judgment, based on the samples that Perseverance has brought back to Earth

13. Question 13 of 20 · Multiple Choice

    Passage 5, paragraph 4: "a few suggest that microbes could survive even today, deep underground." What kind of statement is this?

    AA fact, because scientists have found microbes deep underground on Mars BSpeculation: a possibility no evidence yet shows, signaled by "suggest" and "could" CA reasoned judgment, because the mudstone layers prove that microbes once lived there DA fact, because the passage says that it is warmer deep underground

14. Question 14 of 20 · Multiple Choice

    Which sentence from paragraph 4 of Passage 5 is a statement of fact?

    A"Some scientists think tiny microbes might once have lived there" B"Samples brought back to Earth might one day help answer the question" C"Could anything have lived in those lakes?" D"No life has been found on Mars"

15. Question 15 of 20 · Short Answer

    Rewrite the statement "microbes could survive even today, deep underground" (Passage 5, paragraph 4) as a question that a future mission could test. Then describe a finding that would turn the answer into a reasoned judgment based on research findings.

    Show model answer

16. Question 16 of 20 · Short Answer

    Compare how Lowell (Passage 2, paragraph 1) and the author of Passage 5 (paragraph 4) handle the question of life on Mars. Which one keeps speculation clearly labeled, and how can you tell?

    Show model answer

17. Question 17 of 20 · Multiple Choice

    Passage 5 gives a measured average temperature of about -80 °F. How does this compare with Wallace's reasoned judgment in Passage 4 that Mars is "at least 70° or 80°below the freezing point"?

    AMars is warmer than Wallace thought, so his judgment turned out far too cold BThe two cannot be compared, because Wallace gives his temperatures in Celsius CMars is even colder than Wallace's figure, so his "at least" holds: -80 °F is 112° below freezing DThe two match exactly, because a temperature 80° below the freezing point is the same as -80 °F

18. Question 18 of 20 · Multiple Choice

    Wallace estimated the air of Mars at "one-twelfth (or at most one-seventh)" the density of Earth's air. What does Passage 5, paragraph 2 show about this estimate?

    AMuch thinner than even his lowest figure: 1/12 is about 8 percent; the measured air is under 1 percent BHis estimate was right, because one-twelfth is less than 1 percent of Earth's air CThe air is thicker than he estimated, so Mars is warmer than he thought DHis estimate was right, because the passage says the air of Mars is one-seventh as dense as Earth's air

19. Question 19 of 20 · Multiple Choice

    Lowell wrote that Mars being inhabited was "as certain" as anything (Passage 2). According to Passage 5, what happened to this speculation?

    AIt became a fact when rovers found the canals, filled with dried mud from the ancient lakes BThe canals it rested on turned out not to be real: close-up photographs showed none CIt became a reasoned judgment when rovers found microbes in Gale Crater DIt is still accepted, because Passage 5 says that no one knows about life on Mars

20. Question 20 of 20 · Short Answer

    Passage 5, paragraph 2 says that liquid water "cannot last long on the surface today: in air that thin, it quickly boils away or freezes." This sentence builds on facts. Name the measured facts it depends on, and explain whether the sentence itself is a fact or a reasoned judgment.

    Show model answer

These standards connect to RST.6-8.8: prerequisites to review first, parallel standards at the same level, and next steps that build on it.

Standard text: Common Core State Standards for English Language Arts & Literacy. © Copyright 2010. National Governors Association Center for Best Practices and Council of Chief State School Officers. All rights reserved.