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Class size in the first years at school

Valerie N Podmore

Literature review of recent international research.

Recent research on class size and teacher-pupil ratios can inform policy and practice. Many studies on the impact of class size, and of teacher-student ratios, have concentrated on children's first years at school.

During the 1980s, the research investigated class size and:

  • students' achievement and/or classroom behaviour;
  • teachers' satisfaction and/or stress;
  • classroom organisation;
  • cost effectiveness;
  • the unique features of small classes.

The research methods used to investigate class size became increasingly complex. More recently, research on teacher-pupil ratios and class size emphasises:

  • the features and impact over time of smaller classes;
  • the economics of schooling.

The Impact of Smaller Classes Over Time

Several studies in the United States have tracked students and teachers for a number of years to provide further information about the features and impact of smaller classes. These include: Project STAR, in Tennessee, and Indiana's project PRIME TIME. Project STAR (Student Teacher Achievement Ratio) has received most attention in the recent research literature, and in the popular press.

Project STAR, Tennessee

Project STAR (Student Teacher Achievement Ratio), followed children for 4 years from kindergarten to the third grade. The project was allocated US$12 million government funding over the 4 years, commencing in 1995, and it involved 7,000 students.

Project STAR studied student achievement and development in 3 types of classrooms: small classes with 13-17 students per teacher; regular classes with 22-25 students per teacher; and regular classes with 22-25 students, a teacher, and a teacher aide. Inner-city schools, suburban schools, urban, and rural schools were included in the research. Teachers and students were randomly assigned to the different class types. Findings about student achievement were:

  • Reading and mathematics achievement of students in small classes was significantly higher than that of students in regular classes, from kindergarten to grade 3 level (Nye, 1994);
  • Benefits were found most often among students from ethnic minority groups, who performed almost equally to other students when in small classes, but much lower than other students when in larger classes.

During the course of the STAR 4-year study, over 1,000 teachers took part in interviews held at the end of the school year. Teachers described how small class size benefitted learning and teaching processes:

  • Basic instruction was covered in less time, leaving additional time for introducing further material;
  • There were opportunities to use supplementary texts;
  • Basic content was taught in greater depth;
  • Children had more chances to be involved in "first-hand learning activities";
  • There was an increase in the use of learning centres, and of appropriate teaching practices for primary schools.

The results of the STAR project research led to some strong statements being made about class-size reductions in the early years at school benefitting children and teachers. They also led to reinterpretations and criticisms. The STAR project reports have shown some gaps in information, but smaller classes appear overall to benefit children with special needs, children from minority groups, and younger children during the first years of school. This is achieved through changes to teaching and learning procedures.

The Economics of Schooling

Hanushek's writing on economics and class size effects has had some influence within New Zealand. He disputed the existence and/or magnitude of class size effects on achievement, basing his arguments on recalculations of data. Age-level data are aggregated in many economic re-analyses of class size effects, which effectively camouflages the situation for young children in junior classes in the primary schools. In the one paper accessed where Hanushek does refer to age-related data, he states:

Most studies give no reason to expect a change in student performance as a result of smaller classes...experimental evidence from Tennessee reinforces these results by demonstrating that small classes at best make a discernible difference in kindergarten but not at later primary grades... (Hanushek, 1995, p. 61)

Wenglinsky, at at the Educational Testing Service in the United States, has used a different approach to examining the impact of school spending. He explored the possibility that economic resources and student achievement are linked together through the impact of teacher-student ratios. Wenglinsky's (1997) complex analyses confirm significant, positive relationships between spending on instruction and/or administration and higher ratios of teachers to students. Higher teacher-student ratios showed a significant relationship with school environment, which in turn was related to students' mathematics achievement.

Ratios in New Zealand Primary Schools

In the late 1980s, the 1:20 teacher-to-pupils ratio policy was introduced for junior classes. This staffing policy, a commitment of the Labour government, was implemented in stages, with increased allocations in staffing in 1985, 1986, 1987, and 1991. The 1:20 policy was intended in the shorter term to increase staffing levels in the junior school, to identify appropriate ways in which to allocate staff to schools at each phase, and to develop guidelines for schools about implementation of the policy. The longer term objective of the policy was to enhance learning and teaching. Implementation procedures included a restriction on the creation of new classrooms, and this led to some initial confusion among teachers and parents.

NZCER's evaluation of the implementation of the 1:20 policy surveyed: how the policy was translated into practice, who made decisions about the use of additional staffing, and what teachers saw as outcomes of the policy. Staff in the schools generally supported the policy. The extra staffing provision was used, in part, to staff the Reading Recovery programme, implemented in 1982 to enhance the reading performance of children with learning difficulties in the area of literacy (for further details of this and related New Zealand research, see McDonald, Podmore, Renwick, Smith, Vize, & Wylie, 1989). .

A review of teacher/pupil ratio was commissioned in 1991 to develop a policy for establishing teacher-pupil ratios in the future. The report on the review recommended that: "The continued implementation of the current 1:20 policy should be postponed" (p. 14) and further, the New Zealand State Services commission recommended that: "The current teacher/pupil ratios on which school staffing is based should be suspended" (p.18).

The review drew on a range of research and policy documents. These included the NZCER junior school study, and also a pivotal paper by Hanushek. Hanushek's (1986) paper, which did not separate out the data for younger school-aged children, clearly influenced the recommendation of the New Zealand State Services Commission that "the current (1:20) teacher-pupil ratios should be suspended".

During the early 1990s, the overall ratios of students to teachers gradually started to rise in New Zealand state primary schools: from 19.6 in 1989, to 20.4 in 1994. In late 1994, a Ministerial Reference Group (MRG) was established to work on delivery mechanisms for teaching resourcing. The report of the MRG proposed a system with several recommendations to improve ratios during the early years of schooling. This system was designed:

  • to "enhance the teacher: student ratio" for students in Year 1 to Year 3 in the primary school;
  • to "resolve teacher: student ratios anomalies in schools with rolls between 151-230", and large class size issues in larger primary schools (p. 7).

The core entitlement ratio in Years 1 to 3 of school, to be effective from 1 February 1996, was to be 1:23.

In the 1995 budget the National government approved the lower student-teacher ratios which were recommended by the MGR. New staffing formulae were introduced in 1996. These developments continued under the Coalition (National and New Zealand First) government. By late 1996 as part of the Ministry of Education's 1996/97 School Property Works Programme, the planning and delivery of around 1,200 additional classrooms at existing schools had progressed. Teacher-student ratios started to show some improvement, reducing from 20.7 in 1995, to 19.9 in 1996.

Surveys of primary schools continue to generate data on class size and/or staffing ratios. Some findings on views about class size were reported as part of the New Zealand Council for Educational Research's most recent national survey monitoring the impact of the Tomorrow's Schools reforms (Wylie, 1997). According to the 1997 survey, the MRG staffing formula introduced in 1996 had led to an overall decrease in class size. Parents, and also teachers, wanted smaller class sizes.

Further Research

In New Zealand, concern about staffing ratios in the junior schools remains prominent among teacher groups. The New Zealand Educational Institute (NZEI) has initiated a new survey specifically focused on staffing ratios and class sizes in primary schools. The current entitlement teacher-student ratio remains at 1:23, in keeping with the recommendations of the MRG report.

In the United Kingdom, Blatchford and colleagues note that the scarcity of local evidence about class size effects led to strong assertions from politicians and Secretaries of Education that class size reductions are ineffective. There needs to be longitudinal research, using more complex analyses to overcome some of the limitations of much of the class size research, and to provide sound information as a basis for decisions affecting students and teachers. A longitudinal research project now underway at the Institute of Education in London is collecting both numerical data and in-depth descriptions of children's experiences of class size over time (Blatchford et al., 1998).


During the 1990s, two major connected topics under scrutiny have been: the impact over time of class size, and the economics of schooling. In studies of class size/teacher-student ratios and older students' achievement, the outcomes are not always clear-cut. There is more proof of benefits for younger children. Some of the main points regarding the first years of school are:

  • Smaller classes, and/or higher ratios of teachers to students, can lead to changes in teaching and learning processes and to higher levels of student achievement.
  • When the research is designed to study children and classroom processes, interpretations of the data are likely to demonstrate some valuing of children (and teachers).
  • In New Zealand, the introduction of the 1:20 teacher-pupil ratio policy in the 1980s led to a series of integrated studies of learning and teaching processes in the junior school. The reduction of teacher-student ratios to less than 1:20 appears to be associated positively, but indirectly through classroom processes, with young children's learning and achievement.

Further Reading

Project STAR:

Bain, H. P. & Jacobs, R. (1990). Project STAR research synopsis: The effect of reduced class size on kindergarten reading readiness. ED325235.

Bain, H. P., Achilles, C. M., Zaharias, J. B. & McKenna, B. (November, 1992). Class size does make a difference. Phi Delta Kappan, 253-256.

Finn, J. D. & Achilles, C. M. (1990). Answers and questions about class size: A statewide experiment. American Educational Research Journal, 27, (3), 557-577.

Nye, B. A. (1994). The lasting benefits study: Seventh grade Tennessee Report. Nashville: Tennessee State University.


Gilman, D. A. Swan, E. & Stone, W. (1987). The educational effects of a state supported reduced class size program: A comprehensive evaluation of Indiana's Project PRIME TIME at the north Gibson School Corporation. Contemporary Education, 59, (2), 112-116.

Mueller, D. J., Chase, C. I., & Walden, J. D. (1988). Effects of reduced class size in primary classes. Educational Leadership, 45, (5), 48-50.

a) Limitations/Gaps in the Project STAR Research:
b) New Research Starting in the United Kingdom:

Blatchford, P. & Mortimore, P. (1994). The issue of class size for young children in schools: What can we learn from the research? Oxford Review of Education, 20, (4), 411-428.

Blatchford, P., Goldstein, H., & Mortimore, P. (1998). Research on class size effects: A critique of methods and a way forward. International Journal of Educational Research (special volume).

Prais, S. J. (1996). Class size and learning: The Tennessee experiment—what follows? Oxford Review of Education, 22, (4), 399-414.

The Economics of Schooling: Hanushek, E. A. (1986). The economics of schooling: Production and efficiency of public schools. Journal of Economic Literature, 24,1141-1177.

Hanushek, E. A. (1995, November). Moving beyond spending fetishes. Educational Leadership, 53, (3), 60-64.

Wenglinsky, H. (1997). How money matters: The effect of school district spending on academic achievement. Sociology of Education, 70, (3), 221-237.

New Zealand Research and Policies McDonald, G. (1988). Class size, promotion and policy. New Zealand Journal of Educational Studies, 23, (2), 215-219.

McDonald, G. (1989). Pupil progress, reading recovery and the 1:20 teacher-pupil ratio policy in the junior school. In McDonald, G, Podmore, V. N., Renwick, M., Smith, L., Vize, J. & Wylie, C. (Eds.), More teachers, fewer pupils: A study of the 1:20 teacher-pupil ratio policy in the junior school. Wellington: New Zealand Council for Educational Research.

McDonald, G. Clarke, V. & Kidman, J. (1991). A study of classroom containing five-year-olds. (Junior School Study). Wellington: New Zealand Council for Educational Research.

McDonald, G. Clarke, V. & Kidman, J. (1992a) Five-year-olds and their curriculum. (Junior School Study). Wellington: New Zealand Council for Educational Research.

McDonald, G. Clarke, V. & Kidman, J. (1992b). The first three years: New entrants to J3. (Junior School Study). Wellington: New Zealand Council for Educational Research.

McDonald, G., Podmore, V. N., Renwick, M., Smith, L., Vize, J. & Wylie, C. (Eds.). (1989). More teachers, fewer pupils: A study of the 1:20 teacher-pupil ratio policy in the junior school Wellington: New Zealand Council for Educational Research.

Ministry of Education (1995). Resource entitlement for school staffing: The report of the Ministerial Reference Group Wellington: Ministry of Education.

Podmore, V. N. (1989). Class size: A review of the literature relating to the early years of schooling. In G. Mc Donald, V. N. Podmore, M. Renwick, L. Smith, J. Vize, & C. Wylie (Eds.), More teachers, fewer pupils: A study of the 1:20 teacher-pupil ratio policy in the junior school. Wellington: New Zealand Council for Educational Research.

Podmore, V. N. (1990). Junior school class size: Where are we now? set, no. 1, item 8, 1-4.

Podmore, V. N. (1998). Class size in the first years of school: A New Zealand perspective on the international literature. International Journal Of Educational Research (Special Issue On Class Size, Autumn).

Simpson, J. (1996). New schools and classrooms: 1996/97 accommodation delivery plan. The New Zealand Education Gazette, 75, (21), 1-2.

The Review of the Teacher/Pupil Ratio. (c.1991). Wellington: Unpublished review.

Wylie, C. (1989). Fleshing out the bones: The origins and development of the 1:20 teacher-pupil ratio policy in the junior school. In G. McDonald, V. N. Podmore, M. Renwick, L. Smith, J. Vize, & C. Wylie (Eds.), More teachers, fewer pupils: A study of the 1:20 teacher-pupil ratio policy in the junior school. Wellington: New Zealand Council for Educational Research.

Wylie, C. (1997). Self-managing schools seven years on: What have we learnt? Wellington: New Zealand Council for Educational Research.

Wylie, C. & Smith, L. (1995). Learning to learn: Children's progress through the first 3 years of school. (Junior School Study). Wellington: New Zealand Council for Educational Research.

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Valerie N Podmore