This Is What 16 Research Articles Say About Literacy, Kindergarten, And Entrance Times

I was chatting with a group of friends about kindergarten recently, and realized that there’s been a lot of hype around how kindergarten should be run. Should we be teaching reading in kindergarten? How long should young children be at school? Are private schools with more play time better for development? Has full day kindergarten even helped our struggling readers?

It doesn’t take a lot of looking to find articles pointing out areas that are lacking with our current kindergarten practices. For instance, students in Finland are waiting until later to learn literacy, and their test scores are historically higher than the United States. Another article by the Atlantic shows that our test scores really haven’t increased in 20 years, most likely due to our lack of teaching foundational knowledge for understanding subject matter (or background knowledge). 

So… Are literacy skills in kindergarten actually helping students long term?

The Controversy

The research below is by no way all inclusive. These articles are peer reviewed, were published in high quality journals, and are respected in the education community.

Research that shows increased rigor in kindergarten increases student success:

  • Bruiss (2000) found mixed results whether full day kindergarten resulted in increased academic success, but did find higher test scores for students with disabilities or disadvantages (from poverty, less reading at home, etc.).
  • Elicker (2000) was able to imply full day kindergarten gives academic achievement for longer periods of time with students from low economic status.
  • Northwestern University is one of the only studies that I have found that finds a direct correlation between early skills leading to later academic skills. (However I wonder if this is just is pointing out that students who are “good” at school will still be “good” at school? Again more support that higher income families tend to continue to be successful at school.)
  • Moore was able to find that more preschool increased student’s “emotional knowledge” in grade school when rated from their teachers.

Research that shows increased kindergarten rigor has no effect:

  • Milligan (2012) found that full day kindergarten had no significant effect on reading or math success vs. half day kindergarten. Study was completed in California on a varied sample of students.
  • Barnett (1987) used an economic analysis (widely accepted as the most credible statical methods) on several studies. They wanted to determine if it was cost effective to have early interventions. They found that very few research studies had sound enough statistical models to prove that interventions were cost effective. They did point out that these is still a lot of research left to be done.
  • Hildebrand (2001) studied three different kindergarten schedules and found that length of time in school did not ensure greater test results.
  • Cooper (2010) found that full day kindergarten has a significant effect on academics up until 3rd grade. At that point the effects become negligible. (This was sound similarly on a Head Start research in the 1980’s)
  • Limited conclusions were drawn in Chicago after a long-term study on early interventions. The data was trending in the right direction, but they could not say conclusively if their interventions increased student success.
  • Leow’s (2016) results found that full time head start preschool students did not fair better than half day head start preschool students in kindergarten.

Research that shows increased kindergarten rigor could be problematic:

  • Shephard’s research does NOT point towards rigorous curriculum as causing a negative effect, rather they point out that rigorous academics are inappropriate for young children and that policies such as retention, pre-screening, and moving the age of kindergarten entrance, do more harm because they cause inflated academic rigor.
  • A Special Report from the Annie E. Casey Foundation lays out the numbers and reading scores thoroughly. While this report says that early intervention CAN help students who are disadvantaged, it also points out that raising standards without increasing the quality of education and appropriate education actually widens the gap in performance between high income families and low income families.

Please note: These article’s results do not show direct harm from learning literacy in kindergarten. These found that there were in-advert consequences that could be negative. This is important to note so as not to make conclusions that kindergarten, early academic interventions, or literacy skills are inherently harmful.

Since publishing this article, I have found some research from the Alliance For Children saying that play based learning could actually harm children in the long term. However, I am not sure of the quality of their statical models since I was unable to access the actual research. To look at their reviews check out their article on play gaps and reading instruction. Both articles site peer reviewed research on increased play time increasing academic success into adulthood. 

Research that found increased student success when children wait to start kindergarten:

  • Datar (2006) found that delaying kindergarten by one year boosts test scores. (student enters school at kindergarten level though)

Research that found no difference when children wait to start kindergarten:

  • Narahara, May (1998) was unable to find any difference in academic success by 2nd grade in students who started kindergarten between 4-6 years old.
  • Using the National Education Longitudinal Survey, Lincove found no long term advantages to delaying kindergarten.
  • Lubotsky (2016) found that while older kindergarten entrants tend to grow both cognitively and non cognitively (books smart and emotional smarts) quicker than their younger peers, everyone’s scored tend to even out by second grade.

Research that found waiting too long to start kindergarten could be harmful:

  • Deming was able to conclude that there was no positive effects from delaying kindergarten when using IQ, earnings, and educational attainment as the test. They did however find evidence that delayed kindergarten can hurt outcomes by increasing the likely hood of high school drop out, and overall earnings by a delayed start into the labor market (statistical models were economics based).

Research that found harmful effects of starting kindergarten early:

  • I do not have a link to the original research, but the Foundation for Economic Education reported increased ADHD diagnosis for students who entered school as the youngest were more likely to be diagnosed with ADHD. (However this research is not causal, it’s pointing out a correlation. This means that adults could be over diagnosing children who are still developing.)
  • A study from Australia done by Narahara found that early schooling helped students from low income families cognitively (or academically), but that early schooling hurt all (both low and high income) students in non-cognitive areas.

What Does This Research Mean?

After a lot of reading, I have formed a few opinions from our current understanding of rigorous academics in kindergarten :

  1. We do not have enough research with the most accurate statistical models that prove positive or negative results from increasing time and rigor of kindergarten. Most of these studies say their conclusions are limited.
  2. Early interventions in academics are most beneficial to students who are disadvantaged or have disabilities. However, it appears that these gains might even out by third grade. One scholar proposed placing more supports for those grade levels instead of early interventions.
  3. Overall, rigorous kindergarten is not harmful to students’ future academics, but could take away from other developmental skills like creativity, experiences that increase background knowledge of our world, and social/emotional skills. Background knowledge is leads to greater reading comprehension, and social/emotional skills have direct predictions for adult success. This implies that increased non cognitive skills teaching (like how to speak to an adult, work out problems, and other skills in a way that is most accepted in our country) is just as or more beneficial for disadvantaged students than academic interventions.
  4. Early academic interventions do not negatively impact students in the course of their life time. However there is research that could point to negative impacts when students miss out on creative and play based learning as children.
  5. Student success is still ultimately tied to family income and child exposure to vocabulary, books, and experiences to build on. No research has shown preschool, kindergarten timing, or rigor, to out weigh those family cultural effects on achievement. There is some evidence that play based learning could be a better early intervention.

If The Research Is Somewhat Inconclusive, Why Is The United States Pushing Early Academics?

First, since the United States was first organized, public education was a viewed as an equalizer and a way to allow those in poverty to move up into a higher economic situation.

These ideals have not changed within the US. When Head Start was originally created, it showed huge IQ jumps for students who came from poverty. However they found later that these gains evened out by third grade. Today there is still a large achievement gap between students who are white verses a minority, and students who come from high income families verses low income families.

 Research also shows that students who struggle reading in third grade are at much higher risk for negative adult outcomes. A fantastic review of statistics around third grade reading, implications, and how to fix it, can be found from the free Annie E. Casey Foundation Report. Another easy read about the danger of low reading scores is from HuffPost and the Atlantic.

These facts coupled with the realization that SAT scores haven’t increased in 30 years, 4th grade reading scores have not significantly increased in the past 15 years, and that students who go to college are typically from middle class to upper class families, our government leaders are very concerned about our children who are disadvantaged. And up until this point, providing early interventions for those children is the “low hanging fruit.”

There’s also considerable research done on the amount of vocabulary a child is exposed to while young, directly impacts their academic achievement for the rest of their life. Providing early interventions help young children who are disadvantaged have access to the vocabulary they may be missing.


What do we choose?

Unless your student is showing early delays, you should feel comfortable making an early education decision that works best for your family. Most research is showing no quantifiable negative or positive effect of kindergarten and preschool on achievement.

Research looking at the amount of time spent at kindergarten or preschool did not show any difference in student success. It seemed that the intervention its self was more beneficial for students who were delayed, not the actual amount of time spent in the classroom. This implies that half day kindergarten or preschool is enough for children. On the other hand, full day kindergarten is not harmful, so feel comfortable doing what works best for your family.

The academic success in Finland may have more to do with their culture and less to do with their illiterate kindergarteners. Since wealth is such a strong predictor of success, it’s important note that in Finland, struggling families have more government programs to rely upon. Socialized programs may be allowing citizens less stress about “working their way out of poverty,” and more learning just for the love of it. (This is not a political statement for or against socialized programs or nations)

Other high scoring countries, like Singapore, highly encourage preschool and kindergarten schooling. The big difference between the US and Singapore is the length of the school day. Their school day is shorter than ours but schools typically go year round with about a month long break in the summer. Singapore also has a lot of wealth in their nation. Wealthy families produce situations where students can succeed easier.

Learning to read doesn’t harm our young students, but neglecting time to explore and experience our world could reduce long term comprehension and non cognitive/emotional skills. Additionally, as research on achievement and income point out, our culture puts an emphasis on middle class behaviors (talking “sassy” is disrespectful, looking people in the eye and shaking their hand is encouraged, etc.).

Families who emphasis these “norms” within their own homes are inherently going to help their children be successful. That said, we should still advocate for more non cognitive skills within our schools (or choose to put our children in a different setting that puts an emphasis on this), and include non cognitive skills within whole family interventions.

Implications for our country

Adding play and experiences into early education could help struggling students understand text easier. Comprehension is more tied to linking the text with our understanding of the world, rather than understanding the words we are reading (although, students first need foundational reading skills to even access the print). Increasing those experiences earlier could show overall gains for our disadvantaged students. (refer to this article for more information on changing our teaching for comprehension)

Focusing more on exposure to vocabulary, text and early literacy skills can help students catch up, but these interventions do not need to be in place for the entire day. The time spent in various settings did not show any gains for students. Early academic interventions have not shown to harm students.

Multiple scholars mentioned the need for non cognitive skills in early schooling, and that these skills are predictors for adult success. College graduates all similarly share these skill sets: interact/connect with others, deal with stress, and advocate for themselves. Since the length of time did not show increased achievement, the US education system should be able to find time to incorporate those skills. These skills should especially be emphasized with students who are disadvantaged.

Ultimately, what children need more than anything else, is a home where their parents are engaged and able to provide a safe environment. Families in poverty typically are unable to do that because they constantly in survival mode. If our nation really wants to increase student achievement, we need to focus first on educating and supporting our families who have disadvantages by giving whole family interventions.

Lastly, as a word of caution to parents, I would be careful about getting too tied to any new research claiming a correlation in education. Often times the statistics are not the most accurate and can have very limited results (they cannot be generalized to the entire nation).

As always, I invite comments, questions, and new ideas. 🙂

Research Citations

  1. Barnett, W., & Escobar, C. (1987). The Economics of Early Educational Intervention: A Review. Review of Educational Research,57(4), 387-414. Retrieved from
  2. Christine Leow & Xiaoli Wen (2017) Is Full Day Better Than Half Day? A Propensity Score Analysis of the Association Between Head Start Program Intensity and Children’s School Performance in Kindergarten, Early Education and Development, 28:2, 224-239, DOI: 10.1080/10409289.2016.1208600
  3. Clark, P., Kirk, E., & Burriss, K. G. (2000). Review of research: All-day kindergarten. Childhood Education76(4), 228-231.
  4. Cooper, H., Allen, A. B., Patall, E. A., & Dent, A. L. (2010). Effects of Full-Day Kindergarten on Academic Achievement and Social Development. Review of Educational Research80(1), 34–70.
  5. Datar, A. (2006)
  6. Deming, D., Dynarski, S. (2008) The Lengthening of Childhood. The Journal of Economic Perspectives. 22(3) starting on page 71. Retrieved from
  7. Elicker, J. (2000). Full-Day Kindergarten: Exploring the Research. From Inquiry to Practice. Phi Delta Kappa International, PO Box 789, Bloomington, IN 47402-0789.
  8. Hildebrand, C. (2001). Effects of three kindergarten schedules on achievement and classroom behavior. Phi Delta Kappa Center for Evaluation, Development, and Research. Research Bulletin, no. 31. Bloomington, IN: Phi Delta Kappa. 
  9. Jones D., Greenberg, M., Crowley, M. (2015) Early Social-Emotional Functioning and Public Health: The Relationship Between Kindergarten Social Competence and Future Wellness. AM J Public Health. 105(11). 2283-2290. Retrieved from
  10. Milligan, C. (2012). Full-Day Kindergarten Effects on Later Academic Success. SAGE Open. 
  11. Moore, J., Cooper, B., Rhoades, et al, The Effects of Exposure to an Enhanced Preschool Program on the Social-Emotional Functioning of At-Risk Children. Early Childhood Research Quarterly. 32 starting on page 37.
  12. Narahara, M. (1998) The Effects of School Entry Age and Gender on Reading and Math Achievement Scores on Second Grade Students. The US Department of Education Educational Resources Information Center.
  13. Shepard, L., & Smith, M. (1988). Escalating Academic Demand in Kindergarten: Counterproductive Policies. The Elementary School Journal,89(2), 135-145. Retrieved from
  14. Suziedelyte, A., Zhu, A. (2015) Does Early Schooling Narrow Outcome Gaps For Advantaged and Disadvantaged Children? Economics of Education Review. 45, 76-88. Retrieved from
  15. Vinovskis, M. (1993). Early Childhood Education: Then and Now. Daedalus,122(1), 151-176. Retrieved from
  16. Northwestern University brief:

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