▁public ▁Wi - fi ▁prov iders ▁to ▁block ▁these ▁sites ▁too . ▁ ▁The ▁majority ▁of ▁schools ▁and ▁colleg es ▁use ▁filters ▁to ▁block ▁access ▁to ▁sites ▁which ▁contain ▁adult ▁material , ▁g amb ling ▁and ▁sites ▁which ▁contain ▁mal ware . ▁ ▁YouTube , ▁Facebook ▁and ▁Twitter ▁are ▁often ▁filtered ▁by ▁schools . ▁ ▁Some ▁univers ities ▁also ▁block ▁access ▁to ▁sites ▁containing ▁a ▁variety ▁of ▁material . ▁ ▁Many ▁students ▁often ▁use ▁proxy ▁servers ▁to ▁by pass ▁this . ▁School s ▁often ▁c ensor ▁pup ils ' ▁Internet ▁access ▁in ▁order ▁to ▁offer ▁some ▁protection ▁against ▁various ▁perce ived ▁thre ats ▁such ▁as ▁cy ber - bul lying ▁and ▁the ▁perce ived ▁risk ▁of ▁gro oming ▁by ▁pa ed oph iles ; ▁as ▁well ▁as ▁to ▁maintain ▁pup il ▁attention ▁during ▁IT ▁less ons . ▁ ▁Ex amples ▁of ▁over block ing ▁exist ▁in ▁the ▁school ▁context . ▁ ▁For ▁instance , ▁in ▁February ▁ 2 0 1 4 ▁the ▁website ▁of ▁the ▁Yes ▁Scotland ▁pro - in dep end ence ▁campaign ▁was ▁blocked ▁in ▁a ▁Glasgow ▁school ▁while ▁the ▁rival ▁Better ▁T ogether ▁pro - union ▁website ▁was ▁not ▁blocked . ▁ ▁Pl anned ▁program mes ▁ ▁Ext rem ism ▁ ▁The ▁C ounter ▁T error ism ▁Internet ▁Refer ral ▁Unit ▁( CT IR U ), ▁which ▁was ▁set ▁up ▁in ▁ 2 0 1 0 ▁by ▁the ▁Association ▁of ▁Chief ▁Police ▁Offic ers ▁and ▁run ▁by ▁the ▁Metropolitan ▁Police ▁Service , ▁maintain s ▁a ▁list ▁of ▁sites ▁and ▁content