WWC review of this study

The impact of a supplementary preschool mathematics curriculum on children's early mathematics learning [Numbers Plus Preschool Mathematics vs. business as usual (HighScope)]

Wakabayashi, T., Andrade-Adaniya, F., Schweinhart, L. J., Xiang, Z., Marshall, B. A., & Markley, C. A. (2020). Early Childhood Research Quarterly, 53, 329–342.

  • Randomized Controlled Trial
    , grade

Reviewed: April 2022

No statistically significant positive
Meets WWC standards without reservations
Mathematics outcomes—Indeterminate effect found for the domain
Comparison Period Sample Intervention
Significant? Improvement

Early Mathematics Assessment System (EMAS): Birthday Party (BP) Assessment

Numbers Plus Preschool Mathematics vs. Intervention

0 Days

Full sample;
398 students





Woodcock-Johnson III Tests of Achievement (WJ-III) Applied Problems Subtest

Numbers Plus Preschool Mathematics vs. Intervention

0 Days

Full sample;
417 students





Evidence Tier rating based solely on this study. This intervention may achieve a higher tier when combined with the full body of evidence.

Characteristics of study sample as reported by study author.

  • 7% English language learners

  • Female: 51%
    Male: 49%

  • Rural, Suburban, Urban
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    Maine, Michigan, Ohio
  • Race
    Other or unknown
  • Ethnicity
    Not Hispanic or Latino    


The study took place in various preschool programs in the United States that used HighScope as their primary curriculum. The sample consisted of tuition-based classrooms in Michigan, public school-based classrooms in Maine, and federally funded Head Start classrooms in Ohio. The study was conducted across three years with year 1 in Michigan, year 2 in Maine, and year 3 in Ohio.

Study sample

Students in the sample were 4 years old on average during the study. 49% were male and 7% were English Language Learners. Almost half, 42%, were receiving reduced or free price lunch. Sixty-six percent were White, 22% were Black, 9% were multiracial, and 3% were Asian. Less than 1% of the sample had Hispanic or Latino ethnicity.

Intervention Group

Number Plus consists of 120 small- and large- group activity cards that teachers can implement based on their students' needs and interests. The cards focus on 5 key content areas in mathematics: number sense and operations, geometry, measurement, algebra, and data analysis. Teachers receive instructions for how to conduct activities in each card. These activities were then implemented within the HighScope mathematics curriculum in the study. Each teacher conducted around 7 to 8 Numbers Plus small-group activities per month, consistent with the intended frequency of the developers of the program.

Comparison Group

The comparison condition was business-as-usual. Students in this condition received the HighScope curriculum.

Support for implementation

Teachers received Numbers Plus training and coaching. Training consisted of modules delivered face-to-face for a total of 6 days, and online segments. Teachers were assigned coaches who monitored their progress and helped them implement their goals and activities. Coaches visited classrooms once every 2 weeks in the study, and recorded around 20 coaching contacts per classroom as intended by developers of the program.


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