legitimate peripheral participation describes a mechanismwhereby newcomers to a community of practice constantly move between periph-eral and more central forms of participation. Center and periphery do not referto physical locales but rather to relations of production and accountability crucialfor the community’s functioning.

practice participation results partly from the senseof future that the community imparts to its members.

follows from the child’s identification withfamily and community and his or her ongoing commitment to these

follows from the child’s identification withfamily and community and his or her ongoing commitment to these

person’s understanding of his or her ongoing andfuture relationship to the community and its members, as well as his or her motivesfor engaging the practice in the long run.

distributed framesof cognition (Hutchins, 1995, 1998), norms and values of practice in differentcommunities of amateur astronomers, as well as the division of labor in such com-munities (e.g., Stevens, 2000), create the conditions for and shape individuals’forms of participation.

structuraland process features of the practice, which together afford individuals the ability tocontinuously tailor the hobby: (a) an extensive and varied material infrastructure;(b) participating simultaneously across multiple communities/sites of astronomypractice; (c) activity structural resources that function as templates for short- andlong-term activities; and (d) processes of collaboration and idea sharing.

he availability of distinctsitesandcommunities of practice,each of which espoused a certain instantia-tion of the hobby—that is, a particular substantive focus of astronomy practice,including observations of various kinds, teaching, reading, socializing, and soon—afforded the practitioner the possibility of tailoring his or her practice in avariety of ways

Collaborationwas thus an important dimension of Mitchell’s, Sally’s, and many others’ prac-tices, an inference further strengthened by the ethnographic observations thatinformal and more systematic collaborations were endemic (and thereforeval-ued)at bothMt HillviewandLake Countrysideevents. But it was also clear thatthesocializingfunction ofcollaborationwas at least as important as its products,and individuals clearly used the hobby as a means of developingfriendshipsthatextended beyond the fields of practice.

Specifically, a lens oflines of practicesuggests that,given certainconditions of practice,people will weave all sorts ofpreferencesintoongoing and long-term activities of interest, thus sometimes deviating from theintended curriculum and its topical core, often in dramatic ways

Sharing of resources is key here. Jackie had the most powerful scope in thegroup, and therefore it often served as the primary instrument for their observa-tions, especially when it came to the most faint objects on the list. By comparingviews across many scopes, astronomers could develop a better sense for theirobservations

consider that all amateur astronomers I met inthe field mentioned that completing theMessierlist was a past, present, or futureobservational goal. To be sure, each such individual would do (or did) this indistinct ways: Some observed the objects over a long period of time (say, becausethey pursued multiple simultaneousobservational goals,as was Mitchell’s case),whereas others focused on finishing the list in the least possible amount of time.6

Notice that in many practices in which people participate intensively andextensively (e.g., work and school), at any given time individuals are likely tobe affiliated with a single such community of practice and/or institution

the technological infrastructure that he importedinto his manyobservational linesof practice was clearly continuous with otherpractices beyond amateur astronomy and gave Mitchell’s hobby a flavor that wasdistinctively his.

Taking detailed observationalnoteswas thus a naturalextension of Mitchell’s many other daily practices, and it too shaped and sus-tained his astronomy practice

comparing these notes to Mitchell’s would make very salient the multiple andspecific dimensions of Mitchell’s extended hobby participation.

events such as eclipses, comets, and planet alignments are periodicbut relatively rare, and thus they always attracted Mitchell’s attention, as well asothers’. Likewise, one-time occurrences such as the birth of a nebula are also rareand thus Mitchell and others often took the time to observe them

sites of practice themselves became a case, to be developed inreflexive relation to individual practice cases. In this manner, I hoped to documentidiosyncratic and shared forms of participation within the larger space of prac-tice made available by the hobby as a whole

developing a classroom practice in which par-ticipants (students and teacher alike) see themselves as a community that sharesthe endeavor of learning a discipline.

An individual or personal interest, in contrast, refers to a person’s long-termdisposition to engage a topic or domain—such as world history, the physics ofmotion, or sports—and is usually associated with high knowledge and high valueof such a topic/domain

It follows that becausepeople learn (e.g.,observational skills) along theirlines of practice,intersectionsbetweenlinesshow knowledge and learning that cross line boundaries

preferenceemerging in Mitchell’s narrative regarded hisdevelopingidentityin amateur astronomy

Collaborationwas thus an important dimension of Mitchell’s, Sally’s, and many others’ prac-tices, an inference further strengthened by the ethnographic observations thatinformal and more systematic collaborations were endemic

As is commonly the case, initial coding of the data yielded a very largenumber of categories

ectures, planets(Saturn, Jupiter, Mars,andVenus), theMoon,asteroids, deep sky objects, Messier objects, star clusters, variable stars, dou-ble stars, galaxies, comets, globular clusters, periodical events(e.g.,eclipsesand planetalignments),nebula, Cassiopeia, atlasandcharts, goals

I broaden the descriptiveand explanatory range of these conceptual categories by capturing commonaltiesand idiosyncrasies in practice participation that are the hallmark of interest-basedpursuits.

As she explained,observing M103 followed from her goal of looking at as many “pretty objects”as possible, and she included star clusters as such. As we will see, the themeof observing pretty objects appeared quite frequently in her narratives of thehobby

taking observational notes helps one tolearn about various celestial objects and their defining features and eventually tobetter see such objects (Levy, 1991). Note taking is also a requirement for receiv-ing certificates/awards for certain achievements.

A learning ecology describes a system ofpeople, practices, technologies, and values in a local environment, and individu-als typically participate in multiple such ecologies across time. The frameworkhighlights how people actively create learning opportunities for themselves asthey strive to pursue their evolving interests (in this case, in technological mat-ters), in the process crossing boundaries of several settings (e.g., school, home,and after-school programs). As we will see, tracking how individual hobbyists’practices change over time is one of the methodological/analytical strategiesto inferring the immutable/persistent aspects of people’s short- and long-termpractice, which therefore are central to both a structural and process account ofengaged participation

Suchdetours, which he called “personal excursions,” afforded students the means toforge deeply personal connections to classroom activities and thus served asstrong motivators for students’ continuous pursuits.

hundreds of members, a strong online presence, and a full yearly calendar ofvaried events (e.g., lectures, business meetings, outreach efforts, field trips, and,of course, regular observing practice)

Just what the object of interest-based participation is—that is, what fuelsengagement

the product of which he intendedto submit for the Astronomical League’s Sun Spotter Award. The project wasundoubtedly motivated by Mitchell’s growing curiosity about the Sun and theprospect of receiving the award.

Breaks in the people’s observational routines may also have followed froma number of observation-related occurrences. A common interruption regardedan unusually good sighting of any given

Mitchell’s astronomy activities took place across a number of sites

When he started amateur astronomy,marrying it with his interest in photography was a natural move for him.

presumably in amateur astronomy as well, andthus provide a tangible way for tracing a hobbyist’s motivations for engagingthe practice in the short and long run.

conversations flowed freely between various topics and, naturally, astronomy

Some limited themselves toanswering people’s questions in a private manner, whereas others delivered lec-tures out loud.

Beyond attending to the material means through which astronomers fashiontheir practices, it is important to highlight the materiality of people’s goals asexpressed in the physical (e.g., a planet) and conceptual (e.g., observational skills)objects that themselves become central targets of long-term practice participation

providing favorable conditions for individuals’ interests to take hold and developis a central concern of instructional design. Ensuring support from peers andinstructor as well as allowing students to plan and execute aspects of learningactivities

driving distance

Still, she wanted to make sure that she had spotted the right formation,and thus she began consulting several books in search of a picture of M103 thatcould confirm or reject her inferences

To design instruction for long-term,interest-based engagement, therefore, one begins by surveying students’ broadtopics of interests and then uses such topics to anchor learning activities

deasharing,for both short- and long-termprojectsandgoals,worked in a similar wayto enable the sustaining and extending of a person’slines of practice

short-termprojectsmay feed into long-termgoals,and thisprovides a mechanism for engaging multiplepreferencesacross time.

Practicing at different sites/communities was therefore an expedient wayof tailoring one’s amateur astronomy practice.

everallines of practice, each of which is an expression of clusters of his or her vari-ouspreferencesattuned to certainconditions of practice

Although in this case Sally worked on her own, she and others often collabo-rated on short- and long-term projects or simply consulted with peers for explicithelp. For instance, people often knew the experienced members of the commu-nity, and they might have requested their assistance when they stumbled upon anydifficulties. In addition, because individuals had scopes of different magnification,practitioners often knew whose scope was capable of resolving object featuresthat others’ might not have. So participants often traded viewpoints on theirobservations.

Mitchell stated thathe was not the building type, but he claimed that he could not pass up the opportu-nity of taking a telescope-making course with John Dobson himself—the creatorof what has become a very popular large-aperture telescope.

Star parties at Mt Hillview were quite lively.

given the significant leeway hobbyists have inshaping the content, goals, means, and pace of their activities.

senseof future that the community imparts to its members.

After games or practice, on occasions when the team would go out for pizza. the boys talked minimally about their own games, but primarily about what was happening in the major leagues. The give-and-take, back-and-forth nature of reasoning, arguing, and making a point on and off the field illustrate the dialogical nature of the discourse. The coach assumes an audience of listeners who share his situation and orientation to action and who recognize that talk about baseball is dominant and valid in this context