IB CAS explained: what creativity, activity and service means for your child

What CAS requires

CAS asks each Diploma candidate to engage in a sustained programme of co curricular activity across the two years of the Diploma. The IB requires evidence of regular engagement across three strands: Creativity (the arts, music, drama, creative writing and similar), Activity (sport, physical activity and similar), and Service (community engagement that has a real and measurable impact on others). The IB describes the expected commitment as roughly equivalent to three to four hours per week sustained across eighteen months. There is no minimum number of hours specified in the current syllabus (the old 150 hour benchmark was removed in 2015), but the spirit of the original 150 hour benchmark remains the unofficial guide.

Beyond the strands, CAS asks the student to demonstrate engagement with seven learning outcomes through the body of the portfolio. The seven outcomes are: identify own strengths and areas for growth, undertake new challenges, plan and initiate activities, work collaboratively, show perseverance and commitment, engage with issues of global significance, and consider ethical implications. The portfolio is built around reflective evidence that the student has engaged with each of the seven outcomes through their activities. Reflection, not activity, is the assessment focus.

At least one of the CAS activities must be a CAS Project: a substantive, sustained activity lasting at least one month, involving collaboration with at least one other student, and exhibiting purposeful engagement with one or more of the seven learning outcomes. The Project is intended as the more demanding piece of the portfolio and is often the activity students cite when applying to university.

What strong CAS looks like

Strong CAS is built from activities the student already does or genuinely wants to start, repackaged with appropriate reflection. A student who plays football already has Activity; the CAS contribution is the reflective record of progress, leadership, challenge and ethical engagement through the football season. A student who volunteers at a local food bank already has Service; the CAS contribution is the structured reflection on the service and its impact. Strong CAS does not invent new activities for the portfolio's sake; it asks the student to think clearly about what they are already doing.

Strong CAS is also balanced. A student whose portfolio is heavy on activity and thin on service signals a gap. A student whose service consists of one tokenistic activity rather than sustained engagement signals a gap of a different kind. The CAS coordinator should be checking the balance across the strands and prompting the student to address any thin areas in good time. Schools that do this well meet with each CAS student at three formal interviews across the two years; schools that do it badly meet once and assume the portfolio is on track.

Strong CAS reflections are specific. A reflection that says 'I learned that teamwork is important' is generic and adds nothing. A reflection that says 'I noticed in the spring training season that my passing accuracy dropped when I was tired in the last twenty minutes of each match, so I shifted my conditioning programme to include more sustained interval work in February, and the data from March matches showed the accuracy held up to the final whistle' is specific. The IB rewards the latter. Strong CAS coordinators teach this difference; weak ones accept the former.

What weak CAS looks like

Weak CAS is what happens when the school treats the portfolio as a tick box rather than a developmental experience. Symptoms include: a portfolio assembled in the last term of Year 13 from activities the student barely remembers; reflections written in haste and full of generic learning outcome cliches; a Service strand consisting of a single weekend at a charity event rather than sustained engagement; a CAS Project that is a few hours of group work rather than a meaningful collaborative endeavour. The IB's CAS coordinator network does flag these patterns at moderation and schools that submit consistently weak CAS portfolios are nudged towards better practice, but parents may not see the underlying weakness until the student is in trouble.

Weak CAS can also reflect a student in genuine difficulty. A Diploma student under significant academic pressure may have nothing left over for CAS, and an under structured CAS programme allows the portfolio to slip until it becomes a problem in the spring of Year 13. The fix is structural: a school that bakes CAS into the weekly timetable, an after school activity programme that overlaps with the CAS strands, a sports calendar that runs across both years rather than dropping off at Year 13. Schools that do this take the strain off the student; schools that do not put it on the student.

If your child is at a school with weak CAS structure, the practical response is to build the structure at home. Sit down at the start of Year 12 and map out across the year what activities the child will use for each of the three strands, when reflections will be written (a calendar entry once a fortnight is enough), and what the CAS Project will be. Review the map at half terms. The CAS portfolio assembled this way is rarely the most impressive but it is reliably complete, which is what passes the requirement.

The CAS Project

The CAS Project is the larger collaborative undertaking required of every Diploma candidate. It must run for at least a month, involve at least one other student in a meaningful collaborative capacity, and exhibit purposeful engagement with one or more of the seven learning outcomes. Strong CAS Projects are genuinely substantial: a year long campaign to raise funds and stock a school's first sensory garden, a six month coaching programme run for a younger year group, a documented research and advocacy project on a local environmental issue.

Weak CAS Projects are thin: a few hours of group baking for a charity bake sale, a single weekend cleaning a beach, an organised assembly. The difference between strong and weak is mostly time on task and depth of engagement. A genuine Project should leave the participating students with something they can describe in detail in a university application a year later. A weak Project does not.

The Project is the CAS component most worth investing in. It is the easiest piece of CAS to feature in a university application (the Project lends itself naturally to a 500 word essay), it builds the portfolio's flagship reflective material, and it is the activity that most often shapes the student's sense of what they are capable of organising. Parents who can help the child pick a Project that genuinely interests them are doing the highest leverage CAS work. Our wider IB curriculum explainer covers how CAS fits into the Diploma overall.

How to support a CAS student

The supportive parent's CAS toolkit. First, help with the calendar. The CAS portfolio is small per week and large per year. A fortnightly fifteen minute reflection writing slot, blocked into the calendar, prevents the portfolio from becoming a panic in spring of Year 13. Second, help with the breadth question. Ask the child whether the three strands are balanced, whether the seven learning outcomes are each touched, whether the CAS Project is on track. The CAS coordinator should be asking these questions but parents can supplement.

Second, help the child pick activities they actually care about. CAS is most miserable when the activities are chosen to look good rather than to engage the student. A student spending forty hours in the sixth form on a fundraising drive they hate is a student who would have written better reflections about anything else. The portfolio is built from the student's authentic engagement; nudge the child towards activities that fit their real interests.

Third, stay out of the reflective writing. The reflections must be the student's own. Reading a draft to check for spelling is fine; rewriting the substance is not. The point of CAS is the student's development, and that development is invisible if the parent is doing the reflecting. If the school's CAS coordinator is unresponsive, raise it with the IB coordinator; if the school structure is weak, build the structure at home. Use our IB internal assessment guide for the parallel pattern in the assessed subjects.

Related guides

• International Baccalaureate explained 2026
• IB Extended Essay parent's guide
• Theory of Knowledge explained

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