In the last ten years, there has been a rapid increase in the number of research studies examining the impacts of preschool interventions on children's school readiness outcomes, with many of these studies using rigorous experimental methods that allow attribution of causal relationships. A substantial proportion of these studies have been supported through federal funding, as stand-alone evaluations of federal programs such as the Head Start Impact Study, as part of research initiatives such as the Preschool Curriculum Evaluation Research Initiative, or as individual studies funded through grants. State and local governments, as well as private funders, have also supported recent research studies of preschool interventions. One of the hallmarks of the current crop of research studies is the focus on the right hand side of the equation; that is, the studies are not simply concerned with demonstrating the size of the impacts on child outcomes but also with trying to understand the processes responsible for the impacts that are obtained.
The most recent meta-analyses of early childhood education programs (Jacob, Creps & Boulay, 2004; Nelson & Westhues, 2003; Gorey, 2001; Gilliam & Zigler, 2000) focus on the average size of the impacts of a range of early childhood education interventions. The meta-analyses either bypass the question of variation in instructional inputs as they relate to effect size or focus on programmatic features such as length of day, comprehensiveness of services or auspice rather than instructional methods. However, the research agenda in the past five to ten years has moved beyond proving that early childhood education can make a difference to children, especially at-risk children, to trying to build a body of knowledge about how to successfully intervene with at-risk children to improve their school readiness. The three summary papers discussed here are directly concerned with the most current evidence for instructional practices, interventions, curricula, and programs that have been shown to impact children's development in three domains: language and literacy, math, or socioemotional development.
The question being posed concerns the contributions of this emerging body of research as a source of new evidence or as an extension of what we know about effective interventions for school readiness. On the one hand, the three summary papers suggest that there are an increasing variety of types of early childhood education interventions and curricula that are effective at improving children's school readiness-related outcomes across domains. On the other hand, there are important limitations of the research. First, almost all of the interventions being tested encompass multiple components and the designs do not allow us to "unbundle" these components analytically to determine which programmatic factors make the biggest difference for children's outcomes. When the research is examined for lessons about variation in instruction, the interventions being compared differ on so many factors that it is impossible unable to link outcomes to specific characteristics of instruction or environmental changes. Just as in the past, this current research primarily consists of stand-alone studies, essentially unconnected to one another in any logical way nor connected to a systematic, integrated research plan. At the present time, the research does not go much further in helping us isolate the "potent" or "active" ingredients in instruction that are critical to different child outcomes.
The second limitation is that studies are not connected by a consistent definition of what in fact constitutes school readiness. Studies tend to use measures that align with the intervention and do not attempt to assess a more comprehensive set of outcomes across other domains. This limits our ability to compare the effects of different intervention strategies and to answer questions about whether focusing on one aspect of school readiness (e.g., self-regulation) has generalized impacts across other outcome domains.
Building a systematic knowledge base on effective practices, or a 'science of practice' for promoting school readiness will require an "infrastructure" to guide and link the research. More specifically, the infrastructure will be built on answers to two over-arching questions:
1. What constitutes school readiness?
- Do we understand the foundational skills/content knowledge/understandings that children need to develop by the time they enter school for academic success in both early elementary grades and longer?
- What is the developmental trajectory of these foundational skills?
A common definition of what is meant by "school readiness" will contribute to the ability to standardize the research on school readiness. A justifiable definition of school readiness will depend on evidence showing that skills developed during the preschool period have impacts on later school performance. While each of the three papers offers some rationale for linking the preschool outcomes in their domain to academic outcomes, the rationales are based on a mix of theory, opinions and correlational research. Even in the field of language and literacy, where the soon-to-be-released report from the National Early Literacy Panel will present a comprehensive summary of the research literature about the early or foundational skills/knowledge that are the strongest predictors of later reading achievement, the research base is correlational. Although some of the research reported in these papers will be able to test causal relationships between preschool and school outcomes, assuming long-term follow-up of children, for most of the interventions, it is too early to show long-term effects for children's academic performance and even longer-term social outcomes such as higher education and/or economic productivity. As such evidence is reported, it will be a basis for beginning to build a stronger research-based definition of school readiness. It is worth noting that there are other forces pushing us toward a measurable definition of school readiness. The large scale investments in early childhood through universal pre-kindergarten initiatives and quality improvement systems are being justified in terms of improvements in school readiness. In theory, a definition of school readiness should rest on research linking preschool skills/content knowledge/understandings to later school achievement.
Further, we need longitudinal evidence of the developmental trajectory of skills purported to be foundational.
2. What do we know about the contribution or influence of environmental factors in the development of the foundational skills, and can we build effective interventions based on this knowledge?
- Is there evidence that the skills are learnable or modifiable and therefore susceptible to intervention?
- Based on theory or basic research, can we develop effective interventions to enhance the development of these skills?
- Can we show a causal link between specific instructional practices and student school readiness-related outcomes?
Interventions aimed at enhancing children's school readiness are based on two premises: (a) that the skills being taught or supported by the intervention are learnable, and (b) that there is research or theory to justify the intervention strategies for changing the early childhood education experience so as to alter the developmental trajectory. Even when there is clear agreement on objectives for children at the end of preschool, there are typically alternative theories about effective intervention approaches, as reflected in the variability across intervention designs. This brings us back to the question of which intervention strategies are most powerful in creating changes in children.
The current research is insufficient for understanding the process by which these interventions lead to child impacts. We don't know which of the changes being created in early childhood environments through multi-faceted interventions are the causal factors in changing student outcomes. Even the experimental studies being conducted can't, in fact, establish that the teachers or classrooms that changed the most as a result of the intervention are the same sites where the child outcomes changed the most.
One approach that has been used to begin to build this information base is planned variation research, where the research is designed to systematically test different intervention strategies with similar children and a common set of outcomes, to attempt to isolate which models have the largest impacts. However, unless this type of planned variation research varies and compares the impacts of intervention components rather than multi-dimensional models, it is not possible for the research to provide us with the information we want about mechanisms of change. Further, this kind of planned variation research focuses on the relative contribution of components of the instructional intervention. There are other aspects of the environment that are additional potential factors in the impact of instruction, such as how the classroom is managed (e.g., discipline, grouping), class size and heterogeneity of the child in terms of characteristics such as home language, special needs and the like. Research that allows us to disentangle the combined and individual effects of all of these factors will require complex designs and sample sizes that permit us to test multiple variations.
What follows is an overview of the conclusions from the three synthesis papers about where the current research stands in terms of the content and focus of the interventions being tested, what the findings tell us about effective instructional strategies, and what types of future research will be most informative. The two issues raised above defining school readiness and the developmental trajectory of foundational skills and identifying the active ingredients in interventions will resonate through the overview.
The outcomes of these interventions are discussed in the context of the following domains: socioemotional, language and literacy, and then math. The paper starts with the socioemotional domain because the constituent skills are hypothesized as constituting the platform underlying the child's ability to negotiate successfully all other learning tasks, including early literacy and early math understandings. The second domain discussed is language and literacy. Although language and literacy are often paired, in many respects language should be considered in conjunction with socioemotional development, because of the broad central role language plays in children's learning. For the developing child, the ability to understand and use language is the primary mode by which he builds knowledge of the world and communicates his own ideas and feelings. In this sense, most aspects of socioemotional development are completely intertwined with language development: Children's internalized regulatory mechanisms are language-based, their social understanding is language-based, and their ability to interact and engage with others is primarily negotiated through language. Language development can be labeled as an "engine" of development.
Early literacy and early math are the final outcome areas discussed. As opposed to socioemotional and oral language outcomes, early literacy and math both represent specific skills and understandings. Literacy, for example, includes print knowledge, the alphabetic code and phonological processing (phonological memory, access, and awareness); math includes number and operations with numbers, geometric shapes, spatial relations, and measurement.