Samen Sterk van Start [Starting Strong Together]

Last registered on May 18, 2026

Pre-Trial

Trial Information

General Information

Title
Samen Sterk van Start [Starting Strong Together]
RCT ID
AEARCTR-0018632
Initial registration date
May 13, 2026

Initial registration date is when the trial was registered.

It corresponds to when the registration was submitted to the Registry to be reviewed for publication.

First published
May 18, 2026, 7:16 AM EDT

First published corresponds to when the trial was first made public on the Registry after being reviewed.

Locations

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Primary Investigator

Affiliation
Maastricht University

Other Primary Investigator(s)

Additional Trial Information

Status
In development
Start date
2026-06-01
End date
2029-12-31
Secondary IDs
Prior work
This trial does not extend or rely on any prior RCTs.
Abstract
A significant proportion of novice primary school teachers leaves the teaching profession in the early years of their career. A growing body of evidence shows that structured induction programs can substantially reduce early-career turnover, with mentoring as a key effective component. However, schools facing acute teacher shortages often lack the time and resources to implement high-quality mentoring programs. This study investigates the impact of the program “Samen Sterk van Start” on the outcomes of novice teachers. The program provides an external mentor, who supports beginning teachers with coaching conversations and monthly lesson observations. Using a school-level randomized controlled trial, we estimate the impact of the program on a group of 604 beginning teachers in the Netherlands.
External Link(s)

Registration Citation

Citation
Ruijs, Nienke. 2026. "Samen Sterk van Start [Starting Strong Together]." AEA RCT Registry. May 18. https://doi.org/10.1257/rct.18632-1.0
Experimental Details

Interventions

Intervention(s)
‘Samen Sterk van Start’ is a one-year intensive mentoring intervention designed to support novice teachers during the early phase of their professional career in primary education. Novice teachers are defined as teachers in their first or second year after obtaining their teaching degree.

The aim of the intervention is to reduce attrition among novice teachers by providing structured, high-quality mentoring during this critical induction period. Each participating novice teacher receives 60 hours of mentoring over the course of one school year. The mentoring trajectory consists of biweekly coaching meetings and monthly classroom observations, each followed by a structured post-lesson feedback discussion. Between scheduled sessions, mentors are available via email and phone for additional support. Coaching sessions focus on the further development of professional competencies, including instructional strategies, classroom management, differentiation, and coping with work-related challenges.

Mentors are experienced primary school teachers from other schools within the region and are independent of the school where the novice teacher is employed. Because they have no formal evaluative role in the novice teacher’s school, they provide guidance in a confidential and non-assessing capacity, thereby creating a safe environment for professional learning.

All mentors have at least five years of experience in primary education. They work in roles such as classroom teacher, special needs coordinator, remedial teacher, or school-based teacher educator. Mentors continue teaching part-time to maintain close contact with classroom practice. Most mentors are allocated 0.2 FTE for their mentoring responsibilities, which corresponds to approximately one working day per week. Within this time allocation, each mentor supports five novice teachers. Some mentors are involved in Samen Sterk van Start for less or more time (range 0.08 – 0.4 FTE).

In addition to being selected on their experience, mentors receive a specific training from an Academic Teacher Academy. The training focusses on conversational techniques for mentoring novice teachers, training in classroom observation and the provision of targeted feedback, practice in mentoring conversations through role-play exercises, practice in conducting classroom observations using video recordings of novice teachers and discussing of case studies and practical challenges from professional practice.

To safeguard quality and stimulate continuous professional development, the programme includes a “mentor of mentors.” This senior mentor provides ongoing guidance and is available for consultation when mentors encounter complex cases or professional dilemmas. In addition, peer reflection sessions are organised every two months. During these sessions, mentors collaboratively analyse cases from their mentoring practice and reflect on appropriate strategies and responses. We descriptively analyse the experiences of mentors by measuring mentor job satisfaction and mentor workload.

Mentors and novice teachers are carefully matched based on several criteria, including the type of education (e.g., student population and educational concept), the age group taught, the novice teacher’s specific support needs in relation to the mentor’s expertise, and practical considerations such as geographical distance and working days.

The intervention is targeted towards schools with more disadvantaged students. These schools generally have higher teacher shortages and have less time to provide mentoring for beginning teachers. Specifically, schools are recruited among schools with an above average school weight (school weight >= 30).
Intervention Start Date
2026-08-16
Intervention End Date
2029-07-21

Primary Outcomes

Primary Outcomes (end points)
Novice teacher: teacher turnover (leaving the school)
Primary Outcomes (explanation)

Secondary Outcomes

Secondary Outcomes (end points)
Novice teacher: teacher turnover (leaving the profession), turnover intention, teacher absence, teacher self-efficacy, workload

Students: test scores. Testscores are measured by standardized tests (CITO-LVS) which schools already use. The testscores considered at the class level are Math and Dutch language (comprehensive reading, technical reading and spelling)

Mentor: mentor job satisfaction, mentor workload
Secondary Outcomes (explanation)

Experimental Design

Experimental Design
School*year-level randomized controlled trial
Experimental Design Details
Not available
Randomization Method
Each year, we will recruit a group of schools that employ beginning teachers. Every year, within the recruitment sample of that year and within regions, schools will be randomly allocated to the treatment or control condition using the statistical software R. The stratified randomization within regions is to ensure balanced representation across geographical areas.

The randomization within the region-sample of a specific year is because the trial will be scaled up gradually. As beginning teachers receive one year of mentoring, we can re-randomize schools with new beginning teachers in a later year. In analyzing the results from the pooled (years and region) samples, we will include fixed effects for each group of schools that has been randomized together in a certain year.
Randomization Unit
The treatment will be randomized at the school*year level. Randomization will occur within regions.
Was the treatment clustered?
Yes

Experiment Characteristics

Sample size: planned number of clusters
302 schools
Sample size: planned number of observations
604 schools
Sample size (or number of clusters) by treatment arms
treatment: 302 novice teachers within 151 schools; control: 302 novice teachers within 151 schools. Schools can participate in the trial in different school years if they have new beginning teachers.
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)
Accounting for sample design and clustering, the minimum detectable effect size for the main outcome of teacher turnover is 0.2 SD. This translates to a reduction of 6.6 percentage points in the attrition rates of novice teachers.
IRB

Institutional Review Boards (IRBs)

IRB Name
Vaste Commissie Wetenschap en Ethiek (VCWE) of the Vrije Universiteit Amsterdam
IRB Approval Date
2021-07-01
IRB Approval Number
VCWE-2021-161