“九(jiu)年一(yi)貫(guan)制(zhi)(zhi)”學(xue)校，通常是指(zhi)該校的小(xiao)(xiao)學(xue)和初(chu)(chu)中(zhong)施行一(yi)體化的教(jiao)育，小(xiao)(xiao)學(xue)畢(bi)業后可直升(sheng)本(ben)(ben)校初(chu)(chu)中(zhong)，“小(xiao)(xiao)升(sheng)初(chu)(chu)”原(yuan)則上不(bu)許擇校流動，希望在(zai)本(ben)(ben)校升(sheng)初(chu)(chu)中(zhong)的學(xue)生(sheng)也不(bu)用為上初(chu)(chu)中(zhong)費(fei)盡(jin)心思；九(jiu)年一(yi)貫(guan)制(zhi)(zhi)學(xue)校的年級通常被稱為1年級、2年級……，至9年級。這樣在(zai)學(xue)生(sheng)年齡(ling)較(jiao)小(xiao)(xiao)，適應能力較(jiao)弱(ruo)的時候(hou)的教(jiao)育會有(you)一(yi)個連貫(guan)性(xing)。

"十二年一(yi)貫(guan)制(zhi)學(xue)校"是(shi)指集小學(xue)、初中(zhong)(zhong)(zhong)和高中(zhong)(zhong)(zhong)為一(yi)體的(de)(de)12年一(yi)貫(guan)制(zhi)學(xue)校。學(xue)校主要有三個特點，一(yi)是(shi)連貫(guan)性，學(xue)生可以(yi)從從一(yi)年級(ji)至(zhi)十二年級(ji)，相繼完成小學(xue)至(zhi)高中(zhong)(zhong)(zhong)教育，其間(jian)(jian)不(bu)間(jian)(jian)斷、不(bu)選拔。二是(shi)就近入學(xue)、取消招生考(kao)試。小升初直(zhi)接升入本校初中(zhong)(zhong)(zhong)和高中(zhong)(zhong)(zhong)，不(bu)必(bi)再受小升初、中(zhong)(zhong)(zhong)考(kao)折磨之苦。三是(shi)實行統一(yi)的(de)(de)學(xue)校行政、教育、教學(xue)管理。

“完全中學”既有(you)初級(ji)中學的學段，又有(you)高級(ji)中學學段的學校(xiao)，是一種學校(xiao)制(zhi)度。

初中(zhong)屬于(yu)9年義(yi)務教育階段，而(er)高中(zhong)不(bu)屬于(yu)義(yi)務教育，在(zai)學校的設(she)置中(zhong)，已(yi)經有許多(duo)完全中(zhong)學脫(tuo)鉤為兩所學校。

許多中(zhong)(zhong)(zhong)(zhong)學(xue)(xue)同時設立初(chu)中(zhong)(zhong)(zhong)(zhong)部(bu)及(ji)高中(zhong)(zhong)(zhong)(zhong)部(bu)，這些(xie)(xie)中(zhong)(zhong)(zhong)(zhong)學(xue)(xue)就是完全(quan)(quan)中(zhong)(zhong)(zhong)(zhong)學(xue)(xue)。不過，國(guo)家規定國(guo)家級(ji)重點(dian)中(zhong)(zhong)(zhong)(zhong)學(xue)(xue)和省級(ji)重點(dian)中(zhong)(zhong)(zhong)(zhong)學(xue)(xue)不許開設初(chu)中(zhong)(zhong)(zhong)(zhong)，但(dan)是還是有一(yi)些(xie)(xie)學(xue)(xue)校違(wei)規操作。有一(yi)些(xie)(xie)重點(dian)中(zhong)(zhong)(zhong)(zhong)學(xue)(xue)通過開辦分校等形式開設初(chu)中(zhong)(zhong)(zhong)(zhong)，規避這一(yi)規定。由于歷史的(de)原因，一(yi)些(xie)(xie)曾經(jing)開設初(chu)中(zhong)(zhong)(zhong)(zhong)但(dan)后來(lai)取消了初(chu)中(zhong)(zhong)(zhong)(zhong)部(bu)或者不直(zhi)接開設的(de)，仍(reng)然(ran)被稱為完全(quan)(quan)中(zhong)(zhong)(zhong)(zhong)學(xue)(xue)。