Adaptivity and Flexibility in Multi-digit Arithmetic

Last registered on June 03, 2026
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Pre-Trial

Trial Information

General Information

Title
Adaptivity and Flexibility in Multi-digit Arithmetic
RCT ID
AEARCTR-0018781
Initial registration date
May 31, 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
June 03, 2026, 9:53 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

Name
Helena Skyt Nielsen
Affiliation
Aarhus University
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Other Primary Investigator(s)

PI Name
Lóa Björk Jóelsdóttir
PI Affiliation
VIA University College
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PI Name
Pernille Bødtker Sunde
PI Affiliation
VIA University College
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Additional Trial Information

Status
In development
Start date
2026-06-01
End date
2028-12-31
Keywords
Education
Additional Keywords
Mathematics, teachers, didactic approach, primary- and lower secondary school.
JEL code(s)
I24
Secondary IDs
Prior work
This trial does not extend or rely on any prior RCTs.
Abstract
This project concerns the evaluation of a mathematics intervention in multi-digit arithmetic. The intervention is rolled out as a Randomized Controlled Trial (RCT) in the fall 2026 in around 100 schools in Denmark with the purpose of improving adaptivity, flexibility, accuracy, and mathematics achievement.
External Link(s)

Registration Citation

Citation
Jóelsdóttir, Lóa Björk , Helena Skyt Nielsen and Pernille Bødtker Sunde. 2026. "Adaptivity and Flexibility in Multi-digit Arithmetic." AEA RCT Registry. June 03. https://doi.org/10.1257/rct.18781-1.0
Sponsors & Partners
Experimental Details

Interventions

Intervention(s)
The intervention develops and supports students’ number sense as well as their conceptual and procedural understanding of strategy development in arithmetic.
Intervention Start Date
2026-09-28
Intervention End Date
2026-11-30

Primary Outcomes

Primary Outcomes (end points)
Adaptivity
Primary Outcomes (explanation)
Fraction of tasks solved by a shortcut strategy (phase 1 of the TRIFA test)

Secondary Outcomes

Secondary Outcomes (end points)
See pre-analysis plan
Secondary Outcomes (explanation)

Experimental Design

Experimental Design
Randomization will be conducted at the school level. Schools will be stratified by sector (public/private) and participating grade configuration: grade 3 only, grade 7 only, or both grades. When these groups consist of more than 4 schools, schools are further stratified by percentile rank in the national test score distribution; if schools do not use national tests (i.e. all private schools plus few public schools where information is missing) the percentile rank is instead computed based on average income or education (whichever is most strongly associated with test scores).
Experimental Design Details
Not available
Randomization Method
Randomization done in the office by a computer (Stata with set seed).
Randomization Unit
The clusters are schools. The strata are described above.
Was the treatment clustered?
Yes

Experiment Characteristics

Sample size: planned number of clusters
Around 100 schools
Sample size: planned number of observations
Around 10,000 students.
Sample size (or number of clusters) by treatment arms
Around 50 schools in treatment condition and around 50 schools in control condition.
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)
Supporting Documents and Materials
IRB

Institutional Review Boards (IRBs)

IRB Name
the Institutional Review Board at Aarhus University
IRB Approval Date
2025-08-14
IRB Approval Number
BSS-2025-101-A
IRB Name
the Institutional Review Board at Aarhus University
IRB Approval Date
2025-06-25
IRB Approval Number
BSS-2025-077-S1
Analysis Plan

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