Advertisement

Gramophone record

From Academic Kids

Missing image
Heavenh.jpg
Manufacturers put records inside protective and decorative cardboard jackets and an inner paper sleeve to protect the grooves from dust and scratches. The 12-inch (30 cm) LP vinyl album Heaven and Hell by Black Sabbath is an example, showing the South Korean version of the 33⅓ rpm record from 1980 or 1983.

A gramophone record or phonograph record (often simply record) is an analogue sound recording medium: a flat disc rotating at a constant angular velocity, with inscribed spiral grooves in which a stylus or needle rides. Analogue audio recording onto a disc was the main technology used for the storing of recorded sound for most of the 20th century.

The disc is almost always engraved with a single concentric spiral groove on each side of the disc, running from the outside edge towards the centre. (A small number of early phonograph systems and radio transcription discs started the groove from the inside rather than the edge of the disc, and a small number of novelty records were manufactured with multiple separate grooves.) Since the late 1910s, both sides of the record have usually been used as playing surfaces.

It is most commonly called a "gramophone record" in British English; in American English it is more commonly known as a "phonograph record". Other common names include record, disc, black disc and (more informally) platter or side. 30 cm [~12-inch) 33⅓ rpm vinyl discs were often called long-playing records (or LPs) or albums (LP being a trademark of Columbia Records adopted into common parlance). The term vinyl or vinyl record began to be used in the 1980s, particularly when distinguishing between records and compact discs (CDs), though before the 1950s most records were made of materials other than vinyl.

By the early 1990s digital media such as the compact disc surpassed the gramophone record in popularity, but gramophone records continue to be made (although in very limited quantities) into the 21st century, particularly for DJs doing live remixes and for local acts recording on small regional labels.

Contents

Early history

Recording on disc as opposed to phonograph cylinder had been experimented with by such inventors as Charles Cros, Thomas Edison and Chichester Bell, but the first to actually develop usable disc record technology was Emil Berliner, a German working in Washington, DC, in 1884. He got patents in Berlin and Washington, DC for the record and the gramophone in 1887.

This 1897 hard rubber  plays at about 55 .
Enlarge
This 1897 hard rubber Berliner record plays at about 55 rpm.

The first disc recordings for phonographs or gramophones were commercially marketed in 1895. They gradually overtook the earlier phonograph cylinder as the dominant medium of recorded sound by the 1910s, as they were more economical to produce, less fragile, and easier to store.

Early disc records were originally made of various materials including hard rubber. In the early 20th century earlier materials were largely replaced by a rather brittle formula known as "shellac", actually a mixture of shellac resin (a natural plastic) and cotton or other fiber. The mass production of shellac records began in 1898 in Hanover, Germany. Shellac records were the most common until about 1950. Earliest speeds of rotation varied widely, but by 1910 records rotating at or about 78 or 80 times in one minute became standard, with 78 rpm becoming the standard in the late 1920s. This gave a common name for such records as 78s (or "seventy-eights"). This term did not come into use until after World War II when a need developed to distinguish the 78 from other newer disc record formats. Earlier they were just called records, or when there was a need to distinguish them from cylinders, disc records. Standard records was also used, although the same term had also been used earlier for two-minute cylinders.

In the 1890s the early recording formats of discs were usually 17.5 cm (~seven inches) in diameter. By 1910 the 25 cm (~10-inch) record was by far the most popular standard, holding about three minutes of music or entertainment on a side. 30 cm 12-inch records were also commercially sold, mostly of classical music or operatic selections, with five minutes of music per side.

Such records were usually sold separately, but sometimes in collections held in paper sleeves in a cardboard or leather book, similar to a photograph album, and called record albums. Also, empty record albums were sold that customers could use to store their disc records in.

Missing image
Lp01.jpg
Many records from the mid-1950s and later sported this LP logo indicating their slower speed of 33⅓ rpm.

Post-war formats

After World War II, two new competing formats came on to the market and gradually replaced the standard "78": the 33⅓ rpm (often just referred to as to 33 rpm), and the 45 rpm. The 33⅓ rpm LP (for "long play") format was developed by Columbia Records and marketed in 1948. RCA Victor developed the 45 rpm format and marketed it in 1949, in response to Columbia. Both types of new disc used narrower grooves, intended to be played with a smaller stylus, than the old "78s", so the new records were sometimes called Microgroove. In the mid-1950s all record companies agreed to a common recording standard called RIAA equalization; before then each company had used its own preferred standard, requiring discriminating listeners to use preamplifiers with multiple selectable curves.

The older 78 format continued to be mass produced alongside the newer formats into the 1950s (and in a few countries, such as India, into the 1960s).

About the same time the most common substance for making 33rpm disc records became vinyl, while most 45rpm discs were made from polystyrene. All speeds of records were made in various sizes, mainly 17.5, 25, 30 cm (~7, 10 and 12 inches diameter; the 17.5 cm (~7-inch) being most common for the 45rpm, the 25 cm (~10-inch) for the 78 (and the first few years of 33⅓ production), and the 30 cm (~12-inch) for the 33 from the mid 1950s on.

Missing image
45rpm.jpg
45 rpm records, like this one from 1955, often held a single - one especially popular tune from a particular artist - with a flip side, a bonus for owners.
  • A 45-rpm 17.5 cm (~7-inch) is also called a 45 (forty-five) or a single, because it usually holds a single song on each side. It took over this role from the older standard of the 10-inch 78. Early on RCA sold albums of 45s of all types of music including long classical compositions, but after a few years even RCA recognized that the LP format developed by their competitor Columbia was a more practical format for most recordings other than singles. American 45s have 38 mm (1.5 inch) diameter centre holes. Pressings made in other countries often have 6 mm (0.25 inch)holes, the same as LPs, set into removable 38 mm (1.5 inch) centres.
  • A 45-rpm 30 cm (~12-inch) format was introduced in Britain and America in the late 1970s. These so-called 30 cm (~12-inch) singles can carry extended versions of songs, or carry the same material as regular singles with wider spacing between grooves, allowing for higher sound quality than regular singles.
  • A 33-rpm 17.5 cm (~7-inch) is known as an "EP" (extended play), with 2 or 3 songs per side. However, 45-rpm (17.5 cm (~7-inch) EPs were also produced, using narrower groove spacing (and therefore lower sound quality) to carry two songs per side. In addition, Columbia issued single song per side (17.5 cm (~7-inch) 33-rpm records in 1949 and 1950, hoping to capture the same market that 45-rpm singles were entering.
  • A 33-rpm 30 cm (~12-inch) (originally also 25 cm (~10-inch)) is an "LP" or long-playing record, with 5 to 10 songs on each side. Because the same amount of music as on an entire album of old style 78s could be fitted on a single disc, some people took to calling these new discs albums even when referring to a single disc. The typical playing time of LPs, initially about 15 minutes per side, was soon extended to about 20. "Variable-pitch" recording was introduced in the mid-1950s and conserved recording area by allowing grooves to be spaced more tightly in quiet passages. LP recordings of classical music, in which this technique was very effective, often approached 30 minutes per side. Recordings of popular music, however, were limited to a maximum of about 23 minutes per side (hence the popularity of the C90 compact audio cassette which runs for 45 continuous minutes per side).
  • 16-rpm records, usually 30 cm (~12 inches), were also manufactured. These were of lower audio fidelity and mostly used for spoken word recordings. The most common of these were recorded readings of books made for the benefit of the visually impaired.

In 1958 the first stereo, two channel records were issued - by Audio Fidelity in the USA and Pye in Britain. On stereo records the stylus moves vertically as well as horizontally. Horizontal stylus motion carries the L+R signal, and vertical stylus motion carries the L-R signal. The combined signal is sensed by a left channel coil mounted diagonally opposite the inner side of the groove, and a right channel coil mounted diagonally opposite the outer side of the groove [1] (http://www.vinylrecorder.com/stereo.html). A monophonic recording contains only horizontal modulation and creates equal signal in both channels . Stereo sound provides a more natural listening experience where the spatial location of the source of a sound is, at least in part, reproduced.

The development of quadraphonic records was announced in 1971 - which recorded four separate sound signals. This was achieved on the two stereo channels by electronic matrixing, where the additional channels were combined into the main signal. When the records were played, circuits in the amplifiers were able to decode the signals into four separate channels. There were two main systems of matrixed quadrophonic records produced, confusingly named SQ (by CBS) and QS (by Sansui). They proved commercially unsuccessful, but were an important precursor to later 'surround sound' systems, as seen in SACD and home cinema today. A different format, CD-4 (by RCA), encoded rear-channel information on an ultrasonic carrier, which required a special wideband cartridge to pick it up. Typically the high-frequency information wore off after only a few playings, and CD-4 was even less successful than the two matrixed formats.

Records were extremely popular in their heyday. They were cheap to manufacture, and easy for the buyer to store and play back. In addition to the formats mentioned, numerous less common formats were also produced, often as gimmicks. See: Unusual types of gramophone record

Audiophile records

The record reached its technological peak in the late 1970s just prior to the advent of the digital compact disc. This came in the form of two competing products, direct-cut disc recording and the half-speed mastered album. Small companies like Umbrella in Toronto (1976), and Crystal Clear or Sheffield in California (1977) realized that by dropping the intermediate step of recording to tape, all the potential drawbacks of distortion, noise, and print-through were eliminated. What was lost in convenience and production versatility was gained in higher fidelity. Crystal Clear produced some 12 inch discs at 45 rpm to achieve better high frequency performance. Cutting a master disc direct from the microphone mixing console demands great concentration from the artist, because mistakes cannot be edited out. But the excitement and immediacy of live recording not heard since the early 1950s was evident. Direct-cut discs were limited issue, premium discs because new production masters could not be made when the old ones wore out.

In 1979 another small company, Mobile Fidelity Sound Lab (MFSL), found a way to make higher quality records from tape masters by slowing both the tape transport and cutting lathe to one half normal speed. This reduced distortion by increasing cutting-head amplifier headroom and allowing more accurate groove cutting. MFSL's method was later adopted by other companies including Nautilus and even CBS Records for premium discs.

Both types of audiophile records used other special recording techniques and higher quality materials such as low noise Superdisc vinyl which had been developed by JVC for CD-4 quadraphonic records. Some discs also had heavier mass to reduce the tendency to warp.

The record mastering and pressing process

Recording the disc

For the first several decades of disc record manufacturing, sound was recorded directly on to the master disc (also called the matrix, sometimes just the master) at the recording studio. From about 1950 on (earlier for some large record companies, later for some small ones) it became usual to have the performance first recorded on audio tape, which could then be processed and/or edited, and then dubbed on to the master disc.

A record cutter would engrave the grooves into the master disc. Early on these master discs were soft wax, later on a harder lacquer was used.

Mass producing records

The soft master would then usually be electroplated with a metal, commonly a nickel alloy. When this metal was removed from the master, it would be a negative master (in some companies' terminology, this was called the master; note difference from master disc above). In the earliest days the negative master was used as a mold to press records sold to the public, but as demand for mass production of records grew, another step was added to the process.

The negative master mold is used to create metal positive discs, each called a mother or matrix. These mothers would then in turn be used to make more negatives, each called a stamper. The stampers would be used as the molds for the discs sold to the public. The advantages of this system over the earlier more direct system included ability to make more records more quickly by having multiple stampers pressing records at the same time, more records could be pressed from each record since much used molds would eventually wear out, and spare mothers as back ups.

Disc limitations

Shellac 78s were extremely brittle and would break into several pieces if dropped. This was a very common accident, but one that usually induced a sharp pang of loss. Even careful owners usually lost some records to breakage. In the 1934 novel, Appointment in Samarra, the protagonist—admittedly drunk—

broke one of his most favorites, Whiteman Lady of the Evening... He wanted to cry but could not. He wanted to pick up the pieces. he reached over to pick them up, and lost his balance and sat down on another record, crushing it unmusically. He did not want to see what it was. All he knew was that it was a Brunswick, which meant that it was one of the oldest and best.

A poignant moment in J. D. Salinger's 1951 novel The Catcher in the Rye occurs after the adolescent protagonist buys a record for his younger sister because "I knew it would knock old Phoebe out." But "I dropped the record, and it broke into pieces... I damn near cried, it made me feel so terrible, but all I did was, I took the pieces out of the envelope and put them in my coat pocket."

Vinyl records were less subject to breakage. However, the vinyl material was an effective insulator and very prone to acquiring a static charge and attracting dust, which was very difficult to remove completely. The soft material was easily scratched. Dust and scratches caused audio clicks and pops. In extreme cases, they could cause the needle to skip over a series of grooves, causing the player to skip over a segment of the audio track; or, worse yet, cause the needle to skip backwards, creating a "locked groove" that would repeat the same portion of track over and over again. Locked grooves were not uncommon and were even heard occasionally in broadcasts. Locked grooves formed the subject of jokes ("Machines never make a mistake... make a mistake... make a mistake...") and became a common metaphor (a repetitious complainer might be accused of being "a broken record").

Vinyl records could be warped by heat, improper storage, or manufacturing defects such as excessively tight plastic shrinkwrap on the album. A small degree of warp was common, and allowing for it was part of the art of turntable and tonearm design. "Wow" (once-per-revolution pitch variation) could result from warp, or from a spindle hole that was not precisely centered.

As a practical matter, records provided excellent sound quality when treated with care. They were the music source of choice for radio stations for decades, and the switch to digital music libraries by radio stations has not produced a noticeable improvement in sound quality. Casual ears cannot detect a difference in quality between a CD and a clean new LP played on good equipment. Audiophiles take great care of their records, playing them on expensive equipment to get the best sound and impart the least wear to the disc. However, even with the best of care, keen ears can detect the inherent surface noise. Nevertheless some aficionados believe that under the very best conditions LP sound is superior to CD (see Analog vs. Digital sound argument). The limitations of recording and mastering techniques had a greater impact on sound quality than the limitations of the record itself, at least until the 1980s.

Records were easy and inexpensive to manufacture, so they could be mass-produced. Also, with the advent of long-playing records, the album cover became more than just packaging and protection, and album cover art became an important part of the music marketing and consuming experience.

Missing image
45rpminsert.jpg
Columbia and RCA duked it out in the center of the record. Some turntables included spindle size adapters, but other turntables required snap-in inserts like this one to adapt RCA's larger 45 rpm spindle size to the smaller spindle size available on nearly all turntables.

The "War of the Speeds"

Columbia introduced the 33⅓ rpm LP (long playing) record in 1948. In what has since become an all-too-familiar scenario, their biggest competitor, RCA, deliberately introduced an incompatible format as a competitive marketing maneuver. In addition to having different speeds (33⅓ vs 45), the systems used different record sizes (30 cm and 25 cm vs 17.5 cm (~12 inch and 10 inch vs 7 inch) and a different-sized hole in the center. RCA apparently hoped that consumers would like a system that offered about the same amount of recorded material per disc as the traditional 78s, in a lightweight, compact, higher-fidelity format. Their main consumer offering was a compact, inexpensive 45 changer which had no speakers or amplifier, but was intended to plug into the audio jacks of the then-common console radios and televisions.

RCA's sales declined and in 1950 they capitulated and began using the Columbia format.

By then, phonograph manufacturers had figured out how to cope with the nuisance. Backward compatibility with 78-rpm was important, and if you had to include a two-speed mechanism it wasn't that much more costly to include three. The technical characteristics of 33's and 45's were similar enough to allow use of the same cartridge, stylus, and electronics. By the 1950s most consumer phonographs offered three speeds (78, 45, 33); a single cartridge with a flipover stylus (a single shaft with appropriate stylus for 78's on one side and for microgroove records on the other); and a variety of awkward spindle-size adapters.

Record changers and albums

78-rpm records of popular music were commonly 25 cm (~10 inch)in diameter with a single song on each side. Classical music was commonly recorded on multiple 30 cm (~12 inch) disks. Sets of disks — classical works, collections of popular music, and Broadway shows — were frequently packaged in what were literally albums. These were stiff cardboard boxes containing a bound set of four to six tough paper envelopes, each holding a disc. These envelopes could be turned like pages of a book. Similar albums were available for storage of record collections. In the 1934 Appointment in Samarra, we read the protagonist "got out his favorite records, which were in three albums."

During the 1950s, most popular music was sold in the form of a single 25 cm (~10 inch) 78-rpm record or a single 17.5 cm (~7 inch) 45-rpm record. Popular music was also sold in the form of collections — eight songs by Frank Sinatra on a 10" LP, or twelve on a 30 cm (~12 inch) LP. These single LPs corresponded to an entire album of 78s and were therefore referred to as albums.

The limited playing time of 78 rpm records led to the development of record changers, which allowed stacks of several records to be loaded on a spindle and automatically played in sequence. The purely mechanical mechanisms were ingenious, and most of them were capable of automatically measuring the size of each record as it dropped and positioning the tone arm in the lead-in groove, so that stacks of 17.5 cm, 25 cm, 30 cm (~7 inch, 10 inch, or 12 inch) records could be played automatically. This also led to the invention of the jukebox.

Record changers were provided in most mid-priced consumer phonographs of the 1950s through 1970s. Audiophiles disdained them because of the compromised fidelity resulting from changes in tone arm angle with the height of the stack, and concerns about changers' seemingly rough treatment of discs (particularly slight but cumulative damage to the spindle hole). Changers became rarer in the 1980s.

The numbering of the sides of the discs in some albums and boxed sets of LPs is explained by the fact that they were designed to be played on changers. After the discs were stacked and one side of each disc played, the stack would be turned over together as a unit and replaced on the changer. Thus, to be heard in the proper sequence, the discs of a four-disc set would contain, respectively, "sides" 1 & 8, 2 & 7, 3 & 6, and 4 & 5.

The gramophone record in the era of digital technology

The first commercial digital recordings were made as early as 1972 by Japanese companies such as Denon. These are known as pulse-code modulated (PCM) recordings, and were used to produce analog records because consumer digital playback devices were still ten years in the future.

Beginning with the introduction of the compact disc (CD) in 1982, vinyl records were gradually replaced in mainstream consumer music markets. The CD was effectively a digital re-engineering of the gramophone record by Sony and Philips, using digital codes instead of analog displacements to encode the music waveform, and a non-contact infrared laser sensor instead of a needle. Because of the one-sided technology of the CD, the distinction between "sides" of an album ceased to exist on CD recordings. However, the basic idea of a disk with a spiral groove containing music tracks remained the same.

Vinyl records continue to be manufactured and sold today, although it is considered to be a niche market comprised of audiophiles, collectors, and disc jockeys (DJs). Punk and hardcore bands also often produce their albums and singles on vinyl.

For DJs, mostly in the electronic dance music or hip hop genres, vinyl has one distinct advantage over the CD: the direct manipulability of the medium. While with CDs or cassettes one has only indirect manipulation options (the play/stop/pause etc. buttons), on a record one can put the needle a few tracks farther in- or outwards and accelerate/decelerate the spinning or even reverse the direction (if the needle and record player is built to withstand it).

Many audiophiles dispute the superiority of CDs. The lack of hiss or background crackling is not an inherent quality of CDs, but is dependent on the quality of the original recording. Also the quality and clarity of the sound is very much dependent on the quality of the reproduction equipment, for example the DAC (digital to analog converter).

Some feel that there are inherent limitations with the 44.1kHz sampling rate used for CDs, which may not be a high enough sampling rate to capture subtle phase differences of the psychoacoustic placement of sound in the stereo image. CD recording is limited to a little more than the frequency range of human-audible sounds, with a sharp cutoff before the Nyquist frequency of 22.05 kHz, and many feel that this makes CD-recorded sound "cold": the theory behind this being that non-audible sounds add to analogue recording a "warmth" lacking in CDs. To try to solve this specific problem various solutions have been proposed, like CD players that try to digitally extrapolate non-audible sounds from the recording, and switching to DVD-Audio with its wider frequency range.

More esoteric audiophiles may also state, that instead of just "reproducing" the sound as a CD would, the analogue disc record is able to capture the "real" sound and continue its natural distribution when the record is played.

The background noise one hears on a vinyl record has been compared to the patina of an oil painting -- a part of the work, not an imperfection to be eliminated; moreover, it has been claimed that some pre-CD recordings were made with this patina in mind. To further cloud the issue, some pop music released on CD has had crackles and hiss added artificially, for effect. See Lo-fi. Laser turntables which vacuum clean the vinyl surface before reading it are said to give CD-like clean sound reproducing while preserving all the warmth of analog recording, but they are at the moment extremely expensive for home use.

One argument in favour of vinyl albums is that older recordings were made specifically for vinyl, with equipment specifically calibrated to produce a good-sounding LP. Then, when CDs were introduced, the albums were hastily remastered, and the CD does sound inferior. This is not a fault of the digital medium itself, but rather that the recording was not made to take full advantage of it. Recently, many albums from the pre-CD era (around 1990 or so tends to be the cutoff for when CDs became "the standard" to which recordings were targeted) have been carefully remastered, and sound as good as the original LPs.

See also

Missing image
VoyagerCover.jpg_2big.gif
The Voyager Golden Record

Further reading

  • From Tin Foil to Stereo -- Evolution of the Phonograph by Oliver Read and Walter L. Welch
  • Where have all the good times gone? -- the rise and fall of the record industry Louis Barfe

External links

de:Schallplatte fr:Disque phonographique nl:Grammofoonplaat no:Grammofonplate pl:Płyta_gramofonowa ja:レコード zh:唱片

Navigation

Academic Kids Menu

  • Art and Cultures
    • Art (http://www.academickids.com/encyclopedia/index.php/Art)
    • Architecture (http://www.academickids.com/encyclopedia/index.php/Architecture)
    • Cultures (http://www.academickids.com/encyclopedia/index.php/Cultures)
    • Music (http://www.academickids.com/encyclopedia/index.php/Music)
    • Musical Instruments (http://academickids.com/encyclopedia/index.php/List_of_musical_instruments)
  • Biographies (http://www.academickids.com/encyclopedia/index.php/Biographies)
  • Clipart (http://www.academickids.com/encyclopedia/index.php/Clipart)
  • Geography (http://www.academickids.com/encyclopedia/index.php/Geography)
    • Countries of the World (http://www.academickids.com/encyclopedia/index.php/Countries)
    • Maps (http://www.academickids.com/encyclopedia/index.php/Maps)
    • Flags (http://www.academickids.com/encyclopedia/index.php/Flags)
    • Continents (http://www.academickids.com/encyclopedia/index.php/Continents)
  • History (http://www.academickids.com/encyclopedia/index.php/History)
    • Ancient Civilizations (http://www.academickids.com/encyclopedia/index.php/Ancient_Civilizations)
    • Industrial Revolution (http://www.academickids.com/encyclopedia/index.php/Industrial_Revolution)
    • Middle Ages (http://www.academickids.com/encyclopedia/index.php/Middle_Ages)
    • Prehistory (http://www.academickids.com/encyclopedia/index.php/Prehistory)
    • Renaissance (http://www.academickids.com/encyclopedia/index.php/Renaissance)
    • Timelines (http://www.academickids.com/encyclopedia/index.php/Timelines)
    • United States (http://www.academickids.com/encyclopedia/index.php/United_States)
    • Wars (http://www.academickids.com/encyclopedia/index.php/Wars)
    • World History (http://www.academickids.com/encyclopedia/index.php/History_of_the_world)
  • Human Body (http://www.academickids.com/encyclopedia/index.php/Human_Body)
  • Mathematics (http://www.academickids.com/encyclopedia/index.php/Mathematics)
  • Reference (http://www.academickids.com/encyclopedia/index.php/Reference)
  • Science (http://www.academickids.com/encyclopedia/index.php/Science)
    • Animals (http://www.academickids.com/encyclopedia/index.php/Animals)
    • Aviation (http://www.academickids.com/encyclopedia/index.php/Aviation)
    • Dinosaurs (http://www.academickids.com/encyclopedia/index.php/Dinosaurs)
    • Earth (http://www.academickids.com/encyclopedia/index.php/Earth)
    • Inventions (http://www.academickids.com/encyclopedia/index.php/Inventions)
    • Physical Science (http://www.academickids.com/encyclopedia/index.php/Physical_Science)
    • Plants (http://www.academickids.com/encyclopedia/index.php/Plants)
    • Scientists (http://www.academickids.com/encyclopedia/index.php/Scientists)
  • Social Studies (http://www.academickids.com/encyclopedia/index.php/Social_Studies)
    • Anthropology (http://www.academickids.com/encyclopedia/index.php/Anthropology)
    • Economics (http://www.academickids.com/encyclopedia/index.php/Economics)
    • Government (http://www.academickids.com/encyclopedia/index.php/Government)
    • Religion (http://www.academickids.com/encyclopedia/index.php/Religion)
    • Holidays (http://www.academickids.com/encyclopedia/index.php/Holidays)
  • Space and Astronomy
    • Solar System (http://www.academickids.com/encyclopedia/index.php/Solar_System)
    • Planets (http://www.academickids.com/encyclopedia/index.php/Planets)
  • Sports (http://www.academickids.com/encyclopedia/index.php/Sports)
  • Timelines (http://www.academickids.com/encyclopedia/index.php/Timelines)
  • Weather (http://www.academickids.com/encyclopedia/index.php/Weather)
  • US States (http://www.academickids.com/encyclopedia/index.php/US_States)

Information

  • Home Page (http://academickids.com/encyclopedia/index.php)
  • Contact Us (http://www.academickids.com/encyclopedia/index.php/Contactus)

  • Clip Art (http://classroomclipart.com)
Toolbox
Personal tools