Evidence-Based Studies

Treatment Group/Matched Control Group

The effects of Read Naturally on fluency and reading comprehension: A supplemental service intervention

Heistad, D. (2005)

Four-School Study, Minneapolis, MN

A study of four Minneapolis schools showed that students in Read Naturally programs had significantly greater reading gains than their peers who did not use Read Naturally. The study was based on data collected in Spring 2003 through Spring 2004. Throughout the 2003–2004 school year, one group of students used Read Naturally’s Masters Edition and Software Edition, while one group did not.

A total of 156 students from four Minneapolis schools were included in the study. Each Read Naturally student was matched with a student who was not in a Read Naturally program but had comparable baseline test scores and demographics. The demographic criteria were grade, English language learner status, special education status, free or reduced price lunch status, racial/ethnic category, home language, and gender.

Students who received Read Naturally instruction had improved performance on state-wide tests at statistically significant levels, and a larger proportion of those students met proficiency standards for No Child Left Behind (NCLB) compared to the matched students in the control group. That is, 43% of the Read Naturally students scored at Level 3 or above on the state test (that is, met NCLB standards) compared to 27% of the students in the control group.

This study, known as the Heistad study, demonstrates Read Naturally's long-term impact on comprehension. The National Center on Intervention Intervention (NCII) reported that the Heistad study showed a moderate effect size of .39 on the Minnesota Comprehensive Assessments (MCA) and .24 on the Northwest Achievement Levels Test (NALT). The NCII website provides a summary table of the effect sizes for the Heistad study.

These results are a substantial and academically meaningful measure of Read Naturally's ability to make a statistically significant impact on students' comprehension. The following tables and graphs compare the scores of Read Naturally and control group students on the NALT, MCA, and Reading Fluency Monitor (RFM) assessments.

Average Scores on Three Reading Assessments
Control Group
Read Naturally
Northwest Achievement Levels Test
Baseline (Spring 2003)
Final (Spring 2004)
Minnesota Comprehensive Assessments
Reading Fluency Monitor Assessments
Fall 2003
Winter 2004
Spring 2004
NALT Scores

A comparison of the students’ NALT pre-test scores in Spring 2003 with their test scores in Spring 2004 showed that, on average, the Read Naturally students had gains of 10.8 compared to gains of only 8.3 by students not in a Read Naturally program (see the following graph).

Average Scores on the Northwest Achievement Levels Test

Average Scores on the Northwest Achievement Levels Test

MCA Scores

A comparison of 44 matched pairs of students with MCA scores in grades 3 and 5 showed that students in the the control group had an average score of 1307.3  compared to an average score of 1366.4 for the students in the Read Naturally program (see the following chart).

Average Scores on the Minnesota Comprehensive Assessments

Average Scores on the Minnesota Comprehensive Assessments

RFM Scores

A comparison of the Reading Fluency Monitor scores for 78 matched pairs of students from all four schools (grades 3, 4, and 5) showed that the Read Naturally students increased their scores on benchmark passages by an average of 27.5 points compared to an average increase of 23.2 points for the control group (see the following graph).

Average Reading Fluency Monitor Scores

Average Reading Fluency Monitor Scores

For More Information

pointer Read the complete results of this study


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