LETTERS I BOOKS POLICY FORUM I EDUCATION FORUM I

LETTERSedited by Jennifer Sills

Free Access to Landsat ImageryWE ARE ENTERING A NEW ERA IN THE LANDSATProgram, the oldest and most venerable ofour Earth-observing satellite programs. Withlittle fanfare, the U.S. Geological Survey(USGS) has begun providing imagery forfree over the Internet. Throughout the historyof the Landsat Program, the cost and accessto imagery has always limited our ability 10

study our planet and the way it is changing.Beginning with a pilot program to provide"Web-enabled" access to Landsat 7 images ofthe United States that were collected between2003 and this year, the USGS now plans 10

provide top-quality image products for freeupon request for the entire U.S. archive.including over 2 million images back toLandsat I (1'>72) Itor details and schedules,see (/)1. The release by NASA and the USGSin January 200X of a new Landsat DataDistribution Policy (2) was a key step to thisgoal. Free imagery will enable reconstructionof the history of Earth's surface back to 1072,chronicling both anthropogenic and naturalchanges during a time when our populationdoubled and the impacts of climate changebecame noticeable.

THE LANDSAT SCIENCE TEAM: CURTIS E. WOODCOCK,'* RICHARD ALLEN,2 MARTHA ANDERSON,'ALAN BElWARD,' ROBERT BtNDSCHADLER,s WARREN COHEN,6 FENG GAO,s SAMUEl N. GOWARD,'

DENNIS HElDER," EILEEN HELMER,9 RAMA NEMANI, 10 LAZAROS OREOPOULOS,s JOHN SCH on, 11PRASAD S. THENKABAIL, 12 ERIC F. VERMOTE,1l JAMES VOGElMANN,14

MICHAEl A. WULDER,'s RANDOLPH WYNNE'6

Free image. This Landsat 5 image of the southeast-ern corner of the Black Sea is part of the general

U.S. archive that will be accessible for free under

the new USGS policy.

'Department ot Geography and Environment, Boston University, Boston, MA 02215, USA. 2University 01 Idaho Research andExtension Center, Kimberly, ID 83341. USA. 'USDA-Agricultural Research Service, Hydrology and Remote Sensing Lab,Beltsville, MD 20705, USA.'European Commission loint Research Center, Institute for Environment and Sustainability, GlobalEnvironment Monitoring Unit, 21020, lspra. Varese, Italy.' ASA Goddard Space Flight Center, Greenbelt, MD 20771, USA.{'USDA Forest Service, Corvallis. OR 97331, USA. 'Department of Geography, University of Maryland, College Park, MD 20742,USA. $Electrical Engineering and Computer Science Department, South Da eta State University, Brookings, SD 57007, USA.'International Institute of Tropical Forestry, U.S. Forest Service/Rocky Mountain Research Station, Fort Collins, CO 80526, USA.'''NASA Ames Research Center, Ecosystem Science and Technology Branch, Moffett Field, CA 94035-1000, USA. "RochesterInstitute of Technology, Chester F. Carlson Center tor Imaging Science, Rochester, NY 14623, USA. "International WaterManagement Institute (lWMI), 127, Sunil Mawatha, Battaramulla, Colombo, Sri Lanka. "Department of Geography. University01 Maryland, College Park, MO 20742, USA "SAIClUSGS EROS, Sioux Falls, SO 5 7198, USA. "Canadian Forest Service, PacificForestry Centre, Victoria, Be V8Z 1MS, Canada. '60epartment of Forestry, Virginia Tech University, Blacksburg, VA 24061, USA.

'To whom correspondence should be addressed. E-mail: curtls@bu.edu

References1. USGSTechnical Announcement (htt~:lllalld\at.us9s.90v/illlage5Isqllares/USGS_Landsat_.llllagery ..Release.~df).2. Landsat Missions (http.vldcm.usqv.qovrpdf/IandsatData Policy. pelf).

Why Rowe-Clark Doesn'tTeach by the BookWE ARE WRITING ON BEHALF OF THE 150students attending Rowe-Clark Math andScience Academy, The Exclon Campus ofNoble Street Charter School, and all oftheirteachers. Scienc-e reporter .I. Mavis visitedour campus for several hours this fall toobserve our science and math classes. learnabout our school. and interview students andteachers in preparation for the News Focusstory ""A new bottom line for school science"(22 February. p. 1(30).

Rowe-Clark Math and Science Academy isan exemplary school. showcasing innovative,engaging science and math teaching andlearning. as well as a model partnershipbetween a school and a business, We thankMervis for his aucnt ion to our school and thework we arc doing with Exelon.

l lowever, we feel thai Mervis did a dis-service to Scicncc readers, as wc!l as toRowe-Clark students, teachers. and parents,due to a substuntial-v-and even offcnsive-··error in his reporting.

Mervis reported that freshmen takingphysics at Rowe-Clark do not use a textbook.This is accurate. What is blatantly inaccurateis the reason Mervis cites: "because so manyof them wouldn 't be able to read it." VGalarza explained clearly to Mervis herapproach to teaching physics. and Mervisobserved this during a 2-hour visit to ourphysics classroom. Using the modeling tech-nique, Galarza guides students throughhands-on experiments in which they collectdata and. from that data, derive the laws ofphysics. Students remember what they learnbecause they have discovered it for them-selves. not read it in a textbook. Many of ourstudents are admittedly behind others at theirgrade level. but they art:' able readers who usetextbooks in classes where that is deemed bythe teacher 10 be the best IDOl for learning. Inphysics, active experiments make for morepowerful and lasting learning than textbooks,and the modeling technique is an innovation

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www.sciencemagorg SCIENCE VOL 320 23 MAY 2008Published by MAS

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ILETTERS

in science education that is becoming increas-ingly widespread. It is a student-centeredinstructional strategy through which studentsparticipate in active scientific inquiry. dis-course, and evaluation of evidence,

RACHEl KRAMER AND VANESSA GALARZA

Rowe-ClarkMath and ScienceAcademy, 3645 WestChicagoAvenue, Chicago, Il 60651, USA.

Science Education:Should Facts Come First?IN THEIR EDUCATION FORUM "APPLICATIONof Bloom's taxonomy debunks the' MC ATmyth" (25 January, p. 414), A. Y. Zheng et al .suggest using Bloom 's taxonomy as a tool forassessment of lower- and higher-level think-ing. We think that Bloom's taxonomy shouldbe considered more carefully before it isapplied to the assessment and reform ofundergraduate courses.

B 100l11'staxonomy demonstrates a progres-sive sequence in human cognition, from simple(lower) to complex (higher) thought processes.However, it does not account tor one importantfactor: a temporal or chronological sequence.At different stages of the whole educationalprocess. instructional purposes are different.Assessments should reflect such purposes.Time-consuming lower-level fact instruction atearlier stages will contribute to and guaranteehigher-level thinking. Without assessment oflower-level thinking (that is. the students'knowledge base and comprehension) at stu-dents' earlier stages. instructors may not knowwhether students are well equipped to advanceto concepts that require higher-level thinkingand how far the students could go.

All of the sources used by Zheng et al .

were admission tests or first-year tests. Thegoal of this kind of test is to identity gaps in astudent's mastery of basic facts, and higher-level questions are less effective in meetingthis goal. It may bc unrealistic and dangerousin assessment to jump to a greater proportionof higher-level thinking at the cost of possibleignorance of students' mastery of basic facts.

SHESEN GUO

Oianjianq College, Hangzhou Norrnal University, Hangzhou,Zhejiang 310012, China. E-mail: guoshesen@126.com

ResponseGUO IS CORRECT IN POINTING OUT THAT THEexplicitly hierarchical level of Bloom 's taxon-omy implies a chronological sequence ininstruction (I. 2). The literature docs not,however, support the claim that factual recallshould be the primary focus of early coursesin a curriculum and that higher-order think-ing should be reserved tor later courses. Mosteducators believe that students should beworking at higher levels in Bloom's hierarchyas often as possible. An author on both theoriginal and revised Bloom's taxonomy (I, .7)writes that educational objectives above theFactual Knowledge level "are usually con-sidcrcd the most important goals in educa-tion" [page 213 in (3)]. including primaryand secondary education. The recent revi-sion of Bloom's taxonomy introduces atwo-dimensional framework designed toassess how well the educational objectivesfrom any course fulfill all elements inBloom's framework (2, 3).

ln addition, we arc not aware of datasupporting Guos assertion that "[t jimc-consuming lower-level fact instruction atearlier stages will ... guarantee highcr-Ievelthinking." In our experience. an overcrnpha-

TECHNICAL COMMENT ABSTRACTS

COMMENTON"Brain IRS2 Signaling Coordinates Life Span and NutrientHomeostasis"Colin Selman, Steven Lingard, David Gems, Linda Partridge, Dominic J. Withers

Taguchi et 01. (Reports, 20 July 2007, p. 369) reported that mice heterozygote for a null mutation in insulin recep-tor substrate-2 (Irs2) display a 17% increase in median life span. However, using the same mouse model. we findno evidence for life-span extension and suggest that the findings of Taguchi et 01. were due to atypical life-spanprofiles in their study animals.Full text at www.sciencemag.org/cgi/contentlfull/320/5879/1012b

RESPONSETOCOMMENTON"Brain IRS2 Signaling Coordinates Life Span andNutrient Homeostasis"Akiko Taguchi and Morris F.White

Differences in reported life span of mice heterozygous for a null allele of the insulin receptor substrate-2 (Irs2)might involve the effects of diet, breeding strategies, and genetic background on insulin-like signaling cascades.A better understanding will emerge from studies focusing on the coordination of nutrient homeostasis and life spanby insulin-like signaling in specific peripheral tissues and the central nervous system.Full text at www.sciencemag.org/cgi/contentlfuI1l320/5879/1012c

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Letters to the Editorletters (-300 words) discuss material publishedin Science in the previous 3 months or Issues ofgeneral interest. They can be submitted throughthe Web (wwwsubmitzscience.orq) or by regularmail (1200 New York Ave., NW, Washington, DC20005, USA). Letters are not acknowledged uponreceipt, nor are authors generally consulted beforepublication. Whether published in full or in part,letters are subject to editing for clarity and space.

sis on lower-order thinking at early stages ofinstruction impedes progress in later coursesthat also demand higher-order thinking.Problems arise because students have beentrained to associate memorization with aca-demic success.

Guos letter reflects a view held by asubstantial proportion of instructors thatintroductory science courses should focusprimarily or even exclusively on factual COIl-

tent. The data in our Education Forum(25 January. p. 414) indicated that biologystudents who intend to pursue medical orgraduate school are poorly served by suchcourses because the exams required toradmission emphasize questions above thebottom rung on Bloom's taxonomy.

scan FREEMAN, )ANESSA LAWHORN,ALEX ZHENG

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Department of Biology, University of Washington. Seattle,WA98195, USA.

References1. B.S. Btoom,Ed., Toxonomy 0/ Educational Objectives:

The Ctossijicotio» of Educational Goals. Handbook I:Cognitive Domain (David McKey. NewYork, 1956),

2. l. W. Anderson,D. R. Krathwohl, Eds.,A Taxonomy fOf

iearninq. Teaching, and Assessing: A Revision 0/ Bloom'sTaxonomy 0/ Educational Objectives (Longman,NewYork,2001).

3. D. R. Krathwohl, Theory Pract. 41.212 (2002).

A Victory for PETAAFTER 2 YEARS OF LOBBYING BY PEOPLE FORthe Ethical Treatment of Animals (PETA),CareerBuildcr has stopped its chimpanzeeadvertisement campaign. On 23 January2007, PETA announced online that Career-Builder had agreed to stop this series of adver-tisements; however. CareerBuilder did notsign a pledge to never use great apes in its adsagain (/). Both AAAS (2) and Carecrbuilderhave now made the right move.

CYNTHtA R, SPIESS

Department of Computer Science, Southern IllinoisUniversity, Carbondate, It 62901. USA.

References1. M. McGraw,"CareerBuilderretireschimpanzeeadsfollow-

ing two-yearPETAcampaign" (23 [anuary 2007); www.norncrernonkeybusiness.com/Newsltem1.asp7id=9447.

2. S. R.Rosset 01., Science 319,1487 (2008J.

23 MAY 2008 VOL 320 SCIENCE www.sciencemag.orgPublished by AAAS