Population Design

Population Design

In this technical blog we will look at the language and principles of designing populations within schools. I will begin by defining the terms used then explore the population structures that are used and consider some of the structural implications of each method. This is not a definitive guide but it will give a taste of what decisions need to be considered related to the size of your school.

How we describe populations

When considering the school population organisation it is easy to forget that when the young people walk through the gates in the morning that they are conditioned to go to rooms, halls and gyms with familiar groups of learners, often without thought or effort. How we construct these groups takes careful consideration and understanding to achieve the goals intended. We construct populations within our schools for specific purposes, whether to speak to learners en masse or to teach them. These populations have names embedded in our language, but over 35 years of being involved in educational institutions rarely I have rarely seen them defined, discussed, or evaluated apart from fleetingly on timetabling courses, but they have wider application and importance than just for timetablers. First we must outline the terms so we are clear what we mean.

Key Stage, Year, Band, Stream, House, Class, Group, Set, Form, Tutor. These are all educational terms to describe organisational groups of learners. Some of the words in the list will have specific meaning within the context you know, some of them will have immediately prompted a negative reaction. We have all experienced them in some form during our time within the school system, unless you were home schooled. What I would like to do it simply explore a little of what they mean and why they are significant in the organisation of schools.

Why ‘Population Design?’ Well this is the essence of what we do within all schools – we design the various arrangement of learners for specific purposes, it is the art of designing the orientation of learners for the best effect. Sadly, it is often left to chance (I have even seen it done with a list and a pin!), left to people who have no idea of the impact of the groups they create on teaching and learning or simply ignored and lists of names created are simple the alphabetical list. Others, spend hours pouring over lists of names to get the right mix orientation and ability range for the ‘perfect group’ all of this is about population design, the purposeful organisation of learners into groups.

Defining terms

Lets just offer a short definition of each of the terms so you are clear what I mean by them as the language is often confused between organisations.

Basic concepts of population design.
  • School- The organisation of a group of learners who fall into a range of key stages or Year Groups. These may be described as: Primary (R-Y6), Infant (R-Y2), Junior (Y3-Y6), Lower (R-Y4), Middle (Y5-Y8), Upper (Y9-Y13), Secondary (Y7-Y11/13), Sixth Form (Y12-Y13), UTC (Y10-Y13). There are others but these are the most typical.
  • Key Stage- the national curriculum term for groups of years into phases of learning . The UK system uses 5 key stages covering the years from reception to Year 13.
    • Key Stage 1- Reception to Year 2
    • Key Stage 2- Year 3 to Year 6
    • Key Stage 3- Year 7 to Year 9
    • Key Stage 4- Year 10 and 11
    • Key Stage 5- Year 12 and 13
  • Year Group- the single group of learners who’s birthdays fall between September 1st and August 31st, also referred to as an ‘Academic Year.’
  • Band- the sub-division of a Year Group into mutually exclusive sub-sets of learners. Sometimes referred to as ‘schools within schools.’
  • Stream-the sub-division of Year Groups into bands which have a specific orientation into ability ranges. These often offer significantly different curriculum structures and destination potential and may well be formed based on prior attainment evaluation.
  • House- the organisation of learners from across all available Year Groups into ‘vertically’ oriented populations.
  • Class- The generic term for the sub-division of a band into a number of teaching classes, typically each to have a population of around 30 learners. Sometimes linked to the Form or Tutor Group by nature of the fact that the Form Grouping is the basis for the organisation of the subject teaching. For example the Music teaching may be delivered to a class whose population is the same as the Form Group.
  • Group- Very similar to the description of a Class and often interchanged. Often the terminology refers to bands that are organised into different groupings than the Class to enable different social mixes across the curriculum delivery. The make up of these populations are often described as ‘mixed ability’ where the range prior attainment of learners is distributed across a frame of groups.
  • Set- These are groups that are designed similarly to the definition of the group except that they are structured with very specific ranges of prior attainment. Typical language you will hear will be ‘top set’, ‘bottom set’ where learners have been linearly arranged for the highest prior attainment to be together in the first group and the lowest prior attainment in the last group in the frame.
  • Form- Often seen as the social group as a subdivision of the Year Group. Often the basis of social identity with a Form Tutor who will get to know the learners away from the relationship with the class teachers who will focus on the attendance and behaviour, achievement and discipline of the learners in their journey through the school. In some schools this is referred to as the ‘Tutor Group.’ This organisational format is completely mutually exclusive to the organisational populations above. The fact that a learner is in one Form Group does not mean they have to be in any Band, Class or Set. The only reason for there to be any link would be if the Form Group has a specific time together within the teaching timetable, otherwise they are completely separate.
  • Block- an organisational frame where classes of one subject or multiple subjects are taught together so that they may be ‘set’, i.e. that each class in the block may have a specific population design, ability, prior attainment, gender or other agreed parameter, or organised into individual subject choices, i.e. ‘option blocks.’

The two forms of blocks illustrated in single subject and multi disciplinary modes.

  • Linear frame- an organisational frame where classes of multiple subjects are organised together so that the population of each subject class (horizontal line) is common across the subjects, i.e. history, geography, religious education and citizenship are all taught with the same population design, the same group of learners. In many schools these are mixed ability groupings, socially constructed grouping, e.g. previous school ‘friendship groups,’ or, in some cases, they will be streamed to a high middle and low ability population.

The above arrangement of linear block shows a single group of subjects formed into three class where their populations are common across the frame. The learners stay together for Art, Computing, Drama, French, Geography, German, History, Music and Personal development.

This arrangement of multiple subjects into two frames are derived from 4-class populations. In this case the population design can be different between the two linear frames. One population in the ‘Linear 1’ frame and another in the ‘Linear 2’ frame.

Vertical- this term is used to describe any population that contains learners derived from multiple year groups. Typically, all of the above designations can be designed with vertical populations with houses, tutor groups or forms being the most common. Generally, when these exist outside the timetable cycle they are used to enhance the social cohesion of a school or create a specific identity. However, arrangements for specific purposes can be designed. For example, a school with a very small roll might teach two year groups together to make the class delivery more efficient. A small village primary school might teach Y1 and Y2, Y3 and Y4, Y5 and Y6 in three classes, a small secondary school might teach Y10 and Y11 together to be able to offer a range of options with classes rotating year on year, both real examples of vertical arrangements.

Group level population design

Class level population design

The thorny subject of setting is one that will remain debated as to its real impact but the effect on population design is significant. Within a band we may assume a wide range of ability, the ideal of setting is to reduce the range of ability within a single class/group, The purpose being to enable teachers to focus specific deliver at a smaller range of learners. However, research would suggest that from a learners perspective this only advantages the higher performing learners, a more ideal method might be to enable learners to see and experience their peers engaging at a higher level than they are. This argument might, at the extreme, encourage the organisation of class populations all to fully mixed ability groupings, as illustrated above on the right of the diagrams. However, another approach is to create group populations where learners are able to experience learning above their current demonstrated ability without exposure to the ‘unattainable extreme,’ teachers are able to focus learning on a narrower range of learning than full range mixed ability populations demands. We refer to this population design as ‘Strands’, illustrated above in the centre section. The essence being to to expose learners to learning at a hi than they are currently working at while allowing some streamlining of the mixed ability structures. This process demands a high degree of sophistication in the population design of the classes within a band.

Further reading:

Population design of classes considered within the Education Endowment Foundation Teacher Toolkit.

  • Setting and streaming, link. Negative impact for low cost.
  • Reducing class size, link. Moderate impact for high cost.
  • Within class attainment grouping, link. Moderate impact for very low cost.

Organisation level population design

Single band

School ApplicationSecondary: Up to 150 learners (5 fe)
Primary: Any
Maximum team size 5 specialists

In schools where the year group population is at or below 150, or 5 forms of entry (5fe), it does not normally require sub-division, the use of bands becomes superfluous, the year is the band. In this case all blocks and frameworks for curriculum delivery normally contain the whole year group population so the design of each curriculum element will be mutually exclusive and can have its own rationale. This variation is helpful in many schools to create some community cohesion, learners get to work with other learners. Leaders often express concern about populations that stay the same across the timetable cycle where tensions arise and there is no alternative population experience.

Primary schools

Typically primary schools are structured around this single band model where all classes are in one organisational framework. If the school organises core subjects into sets, for specific teaching purposes, blocking may be used. Learners may have their maths lessons at the same time but not with their normal class, they could be oriented differently for an hour or two taught by a different teacher than their normal class teacher- the population is redesigned for this purpose.

Secondary schools

In small secondary schools each year group is a single band design. Using the 120 4fe example, it would mean that a block of subjects will require four specialist teachers, for example in Maths, English and Science. Each block population may be organised differently, a learner being in group 1 for English, group 2 for maths and group 4 for Science, each block having specific and maybe different rationale for their population designs.

Single population system.

Double band

School ApplicationSecondary: Between 150 learners (5 fe) and 270 learners (9 fe)
Primary: Any
Maximum team size 5 specialists

The next step is when to divide the population? When is it that the structure needs to respond to the demand of specialist subject blocks becomes more than the supply with allow. Double band populations become inevitable when the school has a year group population at or above 180. It is a blurred line and many criteria will impact the decision schools make but the decision to sub divide a year group into two mutually exclusive populations may be at 150 but more typically at 180 and above. For organisations where the roll is set by a PAN which is not divisible by 30 will have many challenges to resolve in terms of efficiency over the balance of the year group numbers. It should be noted that there is no assumption that the two bands created need to be symmetrical in size, obviously a 180 pupil, 6fe, school will easily divide into a symmetrical 90 learners in two bands, but it is quite possible to divide into an asymmetrical arrangement of 120/60, 110/70, 100/80 for whatever reason that can be constructed.

Just to briefly consider the rationale for the different decisions on the division of populations, the main drivers must be equity of delivery and efficiency in the structure. Firstly, it would be difficult to create a banding structure where one population had a significantly different experience than the other without good educational reason. Secondly, there is the question of efficiency. Some structures will have in-built inefficiency simply by means of the number of learners and the sub-divisions that are possible.

Illustrated in the table below is an example of the decision to divide a year group into two populations, the resulting class populations are illustrated against each sub-division. Initially most schools will simply divide in half but you will see in this case that this has an additional cost within Design Technology where class sizes are normally reduced. The most efficient structure is actually the 120/60 division, but this will present the challenge of requiring the existence of 6 Design Technology teachers. A resolution of this might be a further sub-division of the larger population to make two blocks of 3 groups.

Band PopulationsCore and foundation subject Blocks (maximum class size 30)Design and Technology Blocks (optimum class size 20)
90
90
3 groups of 30
3 groups of 30
[6 groups]
5 groups of 18
5 groups of 18
[10 groups]
120
60
4 groups of 30
2 groups of 30
[6 groups]
6 groups of 20
3 groups of 20
[9 groups]
110
70
4 groups of 27.5
3 groups of 23.3
[7 groups]
6 groups of 18.3
4 groups of 17.5
[10 groups]
100
80
4 groups of 25
3 groups of 26.6
[7 groups]
5 groups of 20
4 groups of 20
[9 groups]
Comparison of band population designs for a school of 180 (6fe)

The wider impact of this type of decision to sub-divide a year group into two populations is seen most significantly when there are an odd number of forms of entry. We have considered above that this population design impact with 180 learners (6fe), but consider also where the decision is to divide the population of 150 (5fe) 90/60 not 75/75, 210 (7fe) 120/90 not 105/105, 270 (9fe) 150/120 not 135/135. All of the symmetrical sub-divisions have significant efficiency (and so cost) implications in delivery.

I have discussed the two main drivers being the equity of delivery and inbuilt inefficiency. Another aspect to consider will be the mobility of learners. This considers where there is the potential to change the populations at a micro level (moving learners between groups) and the capacity to do this within the number of groups available. This is where the definitions and understanding of the populations designs begins to make practical impact. If you use setting and there are only two classes in a band- you only have two organisational groups to place learners- this may be too restrictive for some.

Single band system: within each block/frame learners can be moved to other classed so mobility is high.
Symmetrical double band system: within each band learners can be moved to other classes so mobility is equal to the single block system. Learners are not usually moved between bands, but they can be.
Asymmetrical double band system: within each band learners can be moved to other classes but choices are reduced in the smaller band so mobility is unequal. Learners can be moved between bands, however the population in the lower band is at maximum so mobility is significantly reduced.

Triple band

School ApplicationSecondary: Between 270 learners (9 fe) and 450 learners (15 fe)
Primary: n/a
Maximum team size5 specialists

If we consider larger schools there is a significant factor that will impact the logistical delivery of subjects. The issue is the number of specialist teachers available to deliver the single subject blocks.

Large school, two population example.

The above diagram requires significant teams to be available in blocks that may have significant impact on deliverable programmes. It may be that it is fine for core subjects as they will be larger teams in schools of this size. However, it may be more of a challenge to have modern foreign language specialists available together in this way or for there to be sufficient Physical Education capacity in changing rooms for 180 learners or gym, sports hall or outdoor facilities (especially in Winter months) for this quantity of learners.

Large school ,three population example.

In the above example the same large school has reduced the team sizes by dividing to a three band population system. It is the equivalent of organising three small schools operating in a single building.

When we consider these larger schools the opportunity for student mobility is secured, team delivery methodology enables the timetabling principle of ‘the right teacher, with the right group at the right time’ because it allows the capacity related to the larger scale. Below the table provides some view of the capacity required of these larger schools. The threshold where the decision to move to three bands is clearly possible at 270 learners (9fe), there is clearly the capacity to move to 3 bands at 240 learners (8fe), however, it will add efficiency challenges because we are dividing the whole into populations of 80. The challenge will be within the core and foundations subject groups where 3 classes of 26.7 covers a significant proportion of the curriculum model.

Year PopulationsBand PopulationsCore and foundation subject Blocks (maximum class size 30)Design and Technology Blocks (optimum class size 20)
270
(9fe)
90
90
90
3 groups of 30
3 groups of 30
3 groups of 30
[9 groups]
5 groups of 18
5 groups of 18
5 groups of 18
[15 groups]
300
(10fe)
120
90
90
4 groups of 30
3 groups of 30
3 groups of 30
[10 groups]
6 groups of 20
5 groups of 18
5 groups of 18
[16 groups]
300
(10fe)
120
120
60
4 groups of 30
4 groups of 30
2 groups of 30
[10 groups]
6 groups of 20
6 groups of 20
3 groups of 20
[15 groups]
330
(11fe)
120 120
90
4 groups of 30
4 groups of 30
3 groups of 30
[11 groups]
6 groups of 20
6 groups of 20
5 groups of 18
[17 groups]
360
(12 fe)
120
120
120
4 groups of 30
4 groups of 30
4 groups of 30
[12 groups]
6 groups of 20
6 groups of 20
6 groups of 20
[18 groups]
390
(13fe)
150
120
120
5 groups of 30
4 groups of 30
4 groups of 30
[13 groups]
8 groups of 18.75
6 groups of 20
6 groups of 20
[20 groups]
420
(14fe)
150
150
120
5 groups of 30
5 groups of 30
4 groups of 30
[14 groups]
8 groups of 18.75
8 groups of 18.75
6 groups of 20
[22 groups]
450
(15fe)
150
150
150
5 groups of 30
5 groups of 30
5 groups of 30
[15 groups]
8 groups of 18.75
8 groups of 18.75
8 groups of 18.75
[24 groups]
Comparison of band population designs for large schools of 270 (9fe) and over

We will not explore any additional versions of population modelling because all will be a derivation of what we have described above. Any population can be sub-divided into smaller populations for reasons that will be particular to any institution. The impact of this sub-division will be to reduce student mobility between groups, the three structures we have exemplified covers all of the schools in the UK. As a word of caution I would suggest that a significant aspect to consider when designing your populations is to keep the design as simple as possible, remember the adage KISS (Keep it Simple, Stupid!) One of the significant challenges I find when dealing with large schools is where, for very valid reasons the curriculum model ends up with multiple formats, single, double and triple block systems all within one year group.

The first illustration below, Multiple band system 1, is not the most complex we have dealt with but you can see three populations on the left and four to the centre and single populations on the right. This system works within this organisation as it has been acclimatised, however they live with the limitations that it brings in terms of mobility, equity and efficiency, the practices and thinking are embedded and not questioned. When we analyse this we see that there are blocks that can only contain certain learners because the structure dictates. This is the challenge that a simpler system would enable. If you look further in there are some significant efficiency issues created that makes this offer also very costly.

In the second example below, Multiple band system 2, you will see that the double triple combination revolves around PE the need to create the asymmetric is simply a ‘gap filling’ need, the structure creates spaces in the model that have to be filled with a population and the solution is the only way to achieve a logical operational system.

Multiple band system 1
Multiple band system 2

Conclusion

In conclusion, the principles are simple, their application will depend on factors that are not unique to your circumstance but any combination will be specific to your context. Mobility of learners within populations is a key matter for many but the principle concerns will remain to provide the equity and efficiency of provision that ensures curriculum is delivered in the best way that we can provide.

Please feel free to contact us if you need help in shaping your curriculum, contact us by email here.

Published by Chris Jones

CJ Learning Ltd is a collective of education and leadership specialists who bring a level of excellence to their work to make a significant difference in the lives of young people and communities through curriculum development and implementation strategies. CJ Learning Technologies is an Education Technology company providing the SMARTcurriculum Method in the form of an online Application to provide metrics and development strategies for curriculum and staffing provision.