The Prevent Duty and Web Filtering in Schools
What the Prevent duty expects of schools on online radicalisation risk, where web filtering fits, and how to stay proportionate so pupils can still learn about difficult subjects.
Written for designated safeguarding leads, school IT teams and governors in the UK.
What the Prevent duty is
The Prevent duty comes from section 26 of the Counter-Terrorism and Security Act 2015. It applies to named public bodies, which include schools, colleges and registered childcare providers.
In short: specified authorities must have "due regard to the need to prevent people from being drawn into terrorism" when carrying out their work.
Our summary of the statutory duty. The Home Office publishes statutory Prevent duty guidance, updated in 2023 with the new version in force from 31 December 2023. Check the current edition.Who it covers
Maintained schools, academies, free schools, independent schools, FE colleges and early years settings.
Part of safeguarding
Schools treat Prevent as part of their wider safeguarding work, led by the DSL rather than as a separate system.
All ideologies
The duty is not about one group. It covers any ideology that can draw people towards terrorism.
Inspected
Inspectors look at how well a school protects pupils from radicalisation as part of safeguarding.
Keep proportion: block the risk, leave the history lesson open
Prevent filtering goes wrong when it blocks news and teaching along with the genuine risk. Our hosted CIPA filter works by category and lets each school keep its own always-allow and always-block lists on top.
- A school opens one site for a lesson without removing a whole category
- Settings differ by school or branch, so a sixth form need not follow the primary rules
- VPN/Proxy/Anonymizers stays on, so the filter is not simply walked round
What the Prevent duty asks of schools regarding online risk
The guidance groups school expectations into a few practical themes. Online safety runs through all of them, but IT arrangements are where filtering sits directly.
Assess the risk
Understand how likely it is that your pupils could be drawn into terrorism, given your area, age range and known concerns.
Work with partners
Link with local safeguarding partners, the local authority Prevent lead and police where needed.
Train staff
Help staff recognise signs of radicalisation and know how to raise a concern with the DSL.
Safe IT systems
Make sure pupils are kept safe from terrorist and extremist material when they go online at school.
For schools in England, the detail of "appropriate" filtering sits in KCSIE filtering and monitoring requirements and the DfE filtering and monitoring standards. Prevent sets the purpose; those documents set the method.
The role of web filtering in Prevent
Filtering is one layer of protection, not the whole answer. Radicalisation usually happens through people and relationships, often on personal phones the school network never sees.
The police-assessed list of unlawful terrorist content, applied by your filtering provider. Content here is illegal and should never be reachable on school systems.
Blocking categories such as hate, violent extremism and weapons for pupil groups, so new and unlisted sites are also caught.
Spotting searches, repeated block attempts or concerning messages, and passing them to the DSL to consider in context.
Teaching critical thinking, media literacy and British values so pupils can challenge extremist ideas they meet anywhere.
Trained staff, trusted adults and a clear route to the DSL. This is the layer that reaches the phone in a pupil's pocket.
No filter catches everything. The UK Safer Internet Centre's own definitions make this point, which is why teaching and supervision always sit alongside the technology.
Extremism categories versus news and education
The hardest Prevent filtering question is where to draw the line. Pupils need to study terrorism in history, follow the news and discuss current events. Blocking all of that leaves them less prepared, not safer.
Block for pupils
- Unlawful terrorist contentMaterial on the official police-assessed list. Blocked for everyone, with no local override.
- Propaganda and recruitment sitesContent made to promote violent extremist groups or attract supporters.
- Instructional materialGuides to making weapons or carrying out attacks.
- Hate sitesSites that promote hatred or violence against people for who they are.
- Violent goreGraphic real-world violence shared to shock or glorify.
Keep open for learning
- Mainstream news reportingCoverage of attacks, trials and conflicts from established news outlets.
- History and politics resourcesMaterial on the history of terrorism, conflicts and political movements.
- Religious educationFaith sites and resources on beliefs, which are not extremist in themselves.
- Counter-extremism resourcesTeaching materials designed to help pupils challenge extremist narratives.
- Charities and support servicesOrganisations helping people leave extremist movements.
The grey zone: decide locally and write it down
Legal political parties and campaigns, including views staff find uncomfortable. Blocking them can look like taking sides.
Mostly harmless, with pockets of extremist content. Consider safe modes and monitoring rather than blanket blocks.
Older students may need wider access for A level or EPQ work, with a teacher overseeing the request.
Mapping filter categories to Prevent risk
Most filtering systems use categories rather than single sites. This table shows how categories in a typical web filtering taxonomy relate to Prevent, and a sensible starting point for pupil groups.
| Category | Prevent relevance | Pupil default | Notes |
|---|---|---|---|
| Official unlawful terrorist content list | Direct | Always blocked | Supplied through your filtering provider. Not a category you switch off. |
| Hate/Discrimination | High | Block | Covers sites promoting hatred against groups of people. |
| Violence | High | Block | Glorified or graphic violence. Check news sites are not swept in. |
| Weapons | Medium | Block | Weapon sales and instructions. Sport shooting clubs may need review. |
| VPN / Proxy / Anonymizers | Medium | Block | Workarounds let pupils skip every other layer, so they matter for Prevent too. |
| Forums / Message Boards | Context | Review | Some forums host extremist threads. Monitor rather than block all. |
| Social Networking | Context | Review | Decide by age group and policy. Monitoring helps more than blocking here. |
| Political | Low | Allow | Lawful political content supports citizenship teaching. |
| News/Media | Low | Allow | Pupils need reliable news to understand events. |
| Religion & Spirituality | Low | Allow | Faith content is not extremist. Blocking it harms RE teaching. |
| Education/Reference | Low | Allow | Encyclopaedias and study sites often cover terrorism in context. |
Category names here come from our web filtering categories taxonomy. A domain can carry several ranked categories, so a news site reporting on extremism stays in News/Media rather than being treated as extremist.
The categories behind the line you have to draw
Pupils study terrorism in history and follow the news, so a blanket block does harm. The labels below show how sites that look alike to a teacher can land in very different categories.
| Domain | Category in our data | What a school might decide |
|---|---|---|
| bbc.co.uk | News/Media | Keep open for current events |
| iwm.org.uk | Education/Reference | Keep open for history teaching |
| wikipedia.org | Education/Reference | Keep open, teach source checking |
| stormfront.org | Political | A hate site that sits outside the news group, so a school can treat it separately |
| torproject.org | VPN / Proxy / Anonymizers | Blocked with the other bypass tools |
A proportionate approach by age group
Proportion means settings that fit the age, needs and risk profile of the pupils, not one rule for the whole school. Your Prevent risk assessment should inform the choices.
Tight settings. Extremism, hate, violence and weapons blocked, with curated access to news written for children. Close supervision of browsing.
Same protective categories, with more news and reference access. Monitoring of searches becomes more useful as independent research grows.
Access to mainstream news, history and politics resources for GCSE work. Social and forum categories decided by policy.
Wider research access with a clear request route. Official lists and core harmful categories stay blocked at every age.
Over-blocking is a real risk. KCSIE warns against filtering that unreasonably limits what can be taught, and teachers who cannot reach resources often stop teaching the topic.
When monitoring flags something
A flag is a piece of information, not a diagnosis. Curiosity about the news, a history project or a dark joke can all trigger an alert. The DSL decides what it means.
Alert
Search, block attempt or message is flagged by the monitoring system.
Triage
A named person checks the context: lesson, time, device and history.
DSL review
The DSL weighs it with everything else known about the pupil.
Act
Talk with the pupil, inform parents, support in school, or seek advice from partners.
Record
Log the decision and outcome in the safeguarding system.
If the DSL believes a pupil may be at risk of radicalisation, they follow local safeguarding procedures. That may lead to a Prevent referral and the multi-agency Channel programme, which offers support, not punishment.
Working with accredited providers for official lists
Schools do not handle the official terrorist content list themselves. It reaches you through your filtering provider. Ask these questions at procurement and at each annual review.
Do you apply the police-assessed unlawful terrorist content list?Ask for written confirmation and how often it is updated.
Are you an IWF member using its child abuse list?Not Prevent itself, but part of the same baseline for appropriate filtering.
Can school staff disable these lists?They should not be removable locally, even by an administrator.
Have you published a response to the appropriate filtering definitions?The UK Safer Internet Centre hosts provider self-certifications.
How quickly are new extremist domains categorised?Fresh sites appear constantly, so speed matters.
What does your extremism or hate category cover?Ask for a plain description so you can judge over-blocking and gaps.
Does filtering work on devices that leave site?Laptops at home are still school devices.
What reports can the DSL see?Alerts should be readable without IT skills.
Our category database supports filter makers and IT teams with broad, fresh category data. It complements the official lists from accredited providers; it does not replace them. Vendors can read about the web filtering category database or check a site with the domain category checker.
Online signals that staff and systems may notice
No single sign proves a pupil is being radicalised. These are patterns that, together with what staff already know, may be worth passing to the DSL.
Repeated block attempts
The same pupil trying hate or extremist sites again and again, especially outside lesson topics.
Search patterns
Searches that move from news about an event towards group names, symbols or attack methods.
Workaround use
Sudden interest in VPNs, proxies or encrypted apps, which can signal a wish to hide activity.
Language in documents
Slogans, coded terms or dehumanising language appearing in school work or chat on school accounts.
New online contacts
Talk of older online "friends" or groups offering belonging, purpose or a sense of grievance.
Sharing graphic media
Pupils passing round violent videos or memes that mock victims of attacks.
Most of these signals have innocent explanations. Treat them as a prompt for a caring conversation, and keep the focus on the pupil's wellbeing.
Open one source for a lesson, then close it again
Every school in the console has its own always-allow list, and a change applies in seconds. A teacher who needs adult research material can be given a PIN for 15, 30 or 60 minutes, logged, after which the filter switches back.
Common Prevent filtering mistakes
Schools rarely get Prevent filtering wrong through lack of care. The usual problems come from settings nobody has looked at for years, or from blocking out of caution.
| Mistake | Why it matters | Better approach |
|---|---|---|
| Keyword blocking on words like "terrorism" | Stops history homework and news reading while missing coded propaganda. | Rely on site categories and official lists, and use keywords for monitoring alerts instead. |
| Assuming the provider "does Prevent" | Nobody has checked which lists and categories are actually active. | Ask for written confirmation each year and keep it with the review record. |
| Same settings for staff and pupils | Teachers cannot prepare lessons on extremism, or pupils get adult-level access. | Separate group policies with a clear staff request route. |
| Ignoring devices that go home | Most browsing happens off site, often late at night. | Device-level filtering on school laptops and Chromebooks. |
| Alerts with no reader | A flag sits in an inbox for weeks. | Name a reader and a backup, including in holidays. |
| Blocking religion categories | Treats faith as a threat and harms RE teaching and trust. | Keep religion open and block hate and extremist content specifically. |
Prevent across the four UK nations
Arrangements differ by nation. Use this as orientation and check the current guidance for your setting.
England
Prevent duty applies. KCSIE and the DfE standards define appropriate filtering and monitoring.
Wales
Prevent duty applies under the same Act. Welsh Government publishes its own education safeguarding guidance.
Scotland
The duty applies with separate Prevent guidance for Scotland, working within Scottish child protection arrangements.
Northern Ireland
Not covered by the statutory Prevent duty in the same way. Schools follow Northern Ireland safeguarding and online safety guidance.
Prevent and filtering in your annual review
Prevent belongs in the yearly filtering and monitoring review. Bring the Prevent risk assessment to the meeting and test the extremism layers alongside everything else.
Evidence
Provider confirmation of the official list, category settings for hate, violence and weapons, and alert summaries.
Test
Check category blocks from a pupil account with safe test methods, and confirm news and RE sites stay open.
Decide
Record grey-zone decisions, who made them and why. Revisit them next year.
Use our filtering and monitoring annual review checklist to keep a record, and our school web filter test guide for the testing steps.
Prevent filtering by hand or through category settings
Each row follows a point where a school balancing risk and learning often struggles.
| Prevent need | Long lists kept by staff | Hosted CIPA filter |
|---|---|---|
| Keeping up with new sites | Someone adds each address | Sites join categories as we categorize them |
| Settings that fit pupil age | Copies of one list per group | Separate settings per school or branch |
| Letting a lesson use one page | Remove, then remember to re-block | Always-allow entries per site, and a timed PIN for staff |
| Anonymizers and proxies | Patchy lists | VPN / Proxy / Anonymizers is a category, blocked even with a PIN |
| Pupils at home on school laptops | Depends on device set-up | A private encrypted link keeps the rules on the device |
| Showing the review what was done | Exported settings, by hand | Activity reports, policy record and log export |
Prevent duty and web filtering: common questions
Short answers to what DSLs and IT leads ask most.
Does the Prevent duty require schools to filter the internet?
The duty itself is about having due regard to stopping people being drawn into terrorism. The guidance expects pupils to be safe from terrorist and extremist material online at school, and filtering is the normal way to achieve that.
Where does the official terrorist content blocklist come from?
It is produced by police on behalf of the Home Office and shared with filtering providers. Schools receive it through their provider. Ask for written confirmation.
Should schools block all news about terrorism?
No. That is usually disproportionate and stops teachers addressing real events. Keep mainstream news and educational material open and block propaganda, recruitment and illegal content.
Does a monitoring alert about extremism mean a Prevent referral?
Not automatically. The DSL looks at the alert in context and follows safeguarding procedures. Many alerts turn out to be curiosity or schoolwork.
Does the Prevent duty apply across the whole UK?
It applies in England, Wales and Scotland, with separate Scottish guidance. Northern Ireland is not covered in the same way. Check the guidance for your nation.
Can pupils get around Prevent filtering with a VPN?
They can try. Blocking VPN and proxy categories, filtering at device level and monitoring block attempts all reduce this. Mobile data on personal phones needs policy and education instead.
Which school policies should mention Prevent and online safety?
Usually the child protection and safeguarding policy, the online safety policy, acceptable use agreements and the staff code of conduct. Each should describe the filtering and monitoring arrangements in plain language and point to the DSL as the person to contact.
Do teachers need special access to teach about extremism?
Often, yes. A staff policy with wider access, or a quick unblock request route, lets teachers preview resources before a lesson. Record who approved the access and review it each year.
Is filtering enough to meet the Prevent duty?
No. Filtering covers school systems only. Staff training, a clear route to the DSL, work with local partners and a curriculum that builds critical thinking are all part of meeting the duty.
More UK filtering and monitoring guidance
Related guides
The price follows your number of schools and devices, and we answer with a quote inside one business day. A pilot at a single school lets your DSL see what is blocked and what stays open before you decide.
Getting the balance right for your school
Talk to us about your school or trust. We can show how category coverage handles extremism, hate and violence while keeping news and learning resources open.
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