Abstract
This study examines whether the levels of cortisol, a major stress hormone, in kindergarteners are associated with structured English immersion (SEI) in relation to children’s individual differences in temperament. Cortisol levels of 129 kindergarteners (68 boys and 61 girls; 47 in SEI and 82 in non-SEI; mean age=5.30 years) were studied, with salivary samples collected in mid-morning and mid-afternoon, to assess children’s physiological stress responses. The study results show that children’s temperament of externalization/internalization is related to their cortisol level. Results also indicate that, controlling statistically for children’s temperament of externalization and internalization, children in the SEI environment have significantly higher cortisol levels in the mid-afternoon. However, the link between cortisol increase and SEI may reflect the instructional method. As the SEI programs are currently associated with developmentally inappropriate practices, whether children in a more developmentally appropriate SEI program would still have high stress responses needs further research.

Keywords: cortisol, structured English immersion, bilingual education, early childhood education

Introduction
As English education in early childhood programs has become popular in Taiwan, the phenomenon that most English teaching, especially the structured English immersion (SEI) program, does not follow the principle of Developmentally Appropriate Practice (DAP) for young children has caused concerns in the sectors of the government and early childhood education. Most kindergarten SEI programs in Taiwan use English as the primary language for communication and instruction, and the subjects taught include math, science, reading, writing, grammar, art, and physical education, etc. Children usually have two to three lessons every day, and teaching takes up almost all morning time. The SEI programs are mostly teacher-centered, widely employing such methods as learning by heart and reciting, simply following a pre-set curriculum. Time assigned for children’s playing was considered as out-of-lesson time or a break between lessons.
   The effectiveness of Taiwanese SEI programs in early childhood education has not been fully assessed; only sporadic research results exist in this area. A quantitative research shows that children in the SEI programs have higher pupil initiation ratio in teach-children interaction than non-SEI programs (Chiou, Hsieh, Hong, & Li, 2005). However, a qualitative research based on interviews with elementary school teachers suggests that children graduated from the SEI program tend to have adjustment difficulties in learning habits, learning attitudes, and social adaptation (Chen & Chang, 2006). Administrators also suspect that the SEI programs tend to mechanically drill slogans and songs into young children and crowd out basic learning activities essential during the early-childhood learning stage. The Ministry of Education prohibited early childhood programs to offer instruction solely in English since 2004, partly due to the above phenomena and because that most of the foreign teachers in the SEI programs seldom have background in education and early-childhood development (Chen, 2004).
   Early childhood educators suggest that curriculum that is developmentally appropriate for young children should be child-centered and based on what is known from research about child development and how young children learn (Bredekamp & Copple, 1997). The DAP is child-centered and offers children classroom experiences relevant to their lives with hands-on activities, in-depth exploration, cooperative learning, and individualized instruction.
   When one walks into a DAP classroom, the first thing one may notice is the activity of the children. Perhaps they are working on a project such as learning about the noodle shop. Children are talking with each other and discussing and making decisions about their learning. Some may be planning a class trip to a noodle shop, while others are building a checkout stand for the shop they plan to develop in the classroom. Other children may be researching products and pricing for the classroom noodle shop. The teacher facilitates this active learning by assisting each of the groups, questioning the children, and guiding their ideas to help them come to fruition.
   The role of the teacher is to set up an environment where children can learn. The DAP philosophy shifts away from teaching-centered toward a learning-centered one. The challenges for teachers to implement DAP are to incorporate teaching methods that allow children to actively engage in investigations, to observe children’s behaviors and determine what children need and what is their zone of proximal development, and to provide suitable materials or directions to facilitate children’s learning.
   In contrast, the SEI classes in Taiwan are more structured and academically oriented, with more paper-and-pencil activities and less discussion among children and teachers. The flow of a typical class or instructional session of structured English immersion would be like this. Children gather around a native English-speaking teacher, usually a foreigner without an early childhood education background. The teacher first makes the presentation (e.g., drills the children in grammar or spelling), and then he/she would have the children practice. During the practice time, children work individually or in groups, and the teacher circulates, helping individual or groups of students. During the conclusion, children gather around the teacher again, and the teacher would review or ask questions to make sure the students have met the pre-set goals of the instruction before break or play time.
   The trend of more and more kindergartens adopting the less developmentally appropriate practices in the SEI classes has caused great concern for many child development and early childhood education professional in Taiwan. Nationally, there has been an outcry calling for an end to the use of “inappropriate” objectives, activities, and instructional materials in the SEI classes and a shift to “appropriate” methods and materials. As almost all the SEI teachers are foreigners without early childhood education background, it’s a big challenge for the SEI teachers to implement DAP teaching methods. Moreover, most SEI classes in Taiwan adopted a so-called “no Chinese-speaking” policy, hoping to construct an environment which helps children pick up a second language naturally and unconsciously (Cloud, Genesee & Hamayan, 2000; Genesee, 1994). The “no Chinese-speaking” policy and implementation has triggered many concerns about the development of a whole child. A major concern is whether children are under stress when using a foreign language as their primary language for communication and instruction. In this study, we investigate children’s major stress hormone, cortisol, to explore whether the language environment and the developmental appropriateness of the program are related to stress response of young children.

Literature Review
Different Structured English Immersion (SEI) Programs
The term “immersion” was first used to refer to the program used in Canada for French as a foreign/second language for English-speaking children. Canadian-type immersion is bilingual education—development of both languages. It satisfies the three requirements for bilingual education (Krashen, 1996): (1) comprehensible input in the second language; (2) literacy development in the first language; and (3) subject-matter learning in the first language. In addition, because the vast majority of the children in these programs are middle class, they do a considerable amount of reading outside of school (Eagon & Cashion, 1988). Much of the curriculum is in the first language (English), and the goal is bilingualism. The first French immersion program was begun in 1965 in the community of St. Lambert, which is near Montreal, Quebec. The St. Lambert immersion program was set to improve French for English-speaking children who live in Quebec. The immersion program was a joint effort of parent groups, educational authorities, and researchers (Doyle, 2005). However, structured English immersion (SEI) implemented in the US later is somewhat different from the Canadian immersion. SEI uses the first language only minimally and includes direct teaching of the second language grammar and pre-teaching vocabulary (Gersten & Woodward, 1985).
   In Taiwan, English immersion programs for young children have existed for about 20 years. SEI students in Taiwan receive instruction through an English language acquisition process for young children in which nearly all classroom instruction is in English, with curriculum and presentation designed for children who are learning the language. More and more kindergartens in Taiwan have adopted the structured English immersion (SEI) program and become a popular choice for parents who want their children to have the English immersion experience and raise language acquisition efficiency early.
   In these programs, English is the primary language used for communication and instruction. In order to construct an environment in which children use English in multiple contexts, most kindergarten SEI programs in Taiwan also adopt a so-called "no Chinese-speaking" policy. That is, children are not allowed to speak their first language in the school unless they get permission. The rationale of the policy is based upon the belief that one learns a second language by actually communicating through it (Chen, 2006). English is required as the primary communication language among teachers, students, and staff in the school. Also, all subjects are taught mainly in English, for example, science, math, reading, writing, art, and physical education, etc. The integration of language instruction with content instruction is intended to help children pick up a second language naturally and unconsciously (Cloud, Genesee & Hamayan, 2000; Genesee, 1994). 

Developmentally Appropriate vs. Inappropriate Practices in Kindergarten
Both the 1987 and 1997 versions of the American NAEYC guidelines include examples of Developmentally Appropriate Practice (DAP) and Developmentally Inappropriate Practice (DIP). DAP refers to a child-centered approach to instruction that views the child as the primary source of the curriculum and recognizes young children's unique characteristics (Bredekamp & Copple, 1997). Several terms are commonly associated with DAP, including hands-on activities, in-depth exploration, cooperative learning, individualized instruction, and project-based curriculum. Regardless of the chosen strategies, a developmentally appropriate curriculum for young children is child-centered, embraces children's individual differences, encourages active learning, and promotes deep understanding. The curriculum integrates the content areas and provides for active exploration and concrete, hands-on activities. Children are motivated to learn by their natural curiosity and their desire to make sense of the world.
   In contrast, the curricula that emphasize teacher-centered direct instruction are considered less developmentally appropriate. Some research supports the view that the teaching practice of DAP and DIP range from one extreme to the other (Charlesworth, Hart, Burts, Mosley & Fleege, 1993; Stipek, Daniels, Galluzo & Milburn, 1992). The DIP teacher, at another extreme, uses lectures, drill and practice, workbooks, and worksheet activities. DIP separates content areas (i.e., mathematics, science, social studies, reading/language arts, etc.) and has few hands-on, concrete experiences.

Educational Practice and Stress in Kindergarteners
Stress is defined as “the response of the body to any demand” (Selye, 1976) and “a nonspecific response of the body to any demand that exceeds the person’s ability to cope, as a person-environment relationship that threatens or taxes personal resources, and as a mental state in response to strains or daily hassles” (p. 15). In a study exploring educational practices and children’s stress behavior in classrooms, Burts, Hart, Charlesworth, and Kirk (1990) found that children in DIP classrooms exhibited significantly more stress behaviors than children in DAP classrooms. Higher frequency of stress behaviors was found during whole group and workbook/worksheet activities in the inappropriate classrooms. However, the variety of potential stress response and individual differences in expression of emotional intensity makes stress behavior difficult to observe and research (Honig, 1986).
   Recently, concerns about childcare as a stressor for children have been bolstered by the finding that a substantial proportion of children in full-time childcare show atypical stress hormone activity while in care. Increases in cortisol levels throughout the childcare day have been reported in many children, whereas cortisol levels tend to follow a typical circadian decrease from morning to afternoon when measured in the same children at home on weekends (Dettling, Gunner, & Donzella, 1999; Tout, de Haan, Campbell, & Gunnar, 1998; Watamura, Sebanc, & Gunnar, 2002). Cortisol elevations throughout the day are of potential concern because chronic activation of the hypothalamic-pituitary-adrenocortical (HPA) system, which produces cortisol, has been found to have negative effects. The negative consequences include compromised immune system functioning (Boyce, Adams, Tschann, Cohen, Wara, Gunnar, 1995) and brain structures involved in memory and learning (Seeman & McEwen, 1996) and future vulnerability to anxiety and depressive disorders (Heim, Owen, Plotsky, & Nemeroff, 1997).
   As the improved measurement techniques allow physiological assessment of neuroendocrine activity in children, the study of children’s physiological response to stress has been a renewed interest in the last decades. Linkages between the HPA system, personal disposition, and environmental influences on children have been of interest to developmental psychologists. Areas of ongoing exploration include stress reactivity in relationship to a variety of variables such as children’s temperament (Dettling, Gunnar, & Donzella, 1999; Gunnar, Mangelsdorf, Larson, & Hertsgaard, 1989), behavioral development and adjustment (Blair, Granger, & Razza, 2005; Smider, Essex, Kalin, Buss, Klein, Davidson, & Goldsmith, 2002; Watamura, Donzella, Alwin, & Gunnar, 2003; Watamura, 2004), mother-child attachment (Gunnar, Mangelsdorf, Larson, & Hertsgaard, 1989), and length and quality of child care (Dettling, Gunnar, & Donzella, 1999; Gunnar & Donzella, 2002).
   Crockenberg (2003) suggested that children’s individual differences in stress responses to full-time, center-based childcare are associated with emotional tendencies that may precede their entry into early childhood programs and need to be considered. Children’s temperaments, a factor that may influence differences in children’s responses to childcare, should be studied (Crockenberg, 2003; Watamura, Donzella, Alwin, & Gunnar, 2003). Using infants and toddlers as subjects, Watamura, Donzella, Alwin, and Gunnar (2003) presented evidence that teacher-reported fearfulness is associated with larger cortisol increases during the day, and Dettling, Parker, Lane, Sebanc, and Gunnar (2000) reported that a daytime cortisol increase was greater for more emotionally negative children and for those with lower self-control.  
   Moreover, the finding that cortisol increased more over the day when the quality of care was low suggests that childcare quality or context may be a confounding variable in the study of childcare effect. Complex interplay may exist between the amount, type, and content of childcare that, in conjunction with children’s temperamental characteristics, predict differences in physiological stress response among young children in full-day childcare (Crockenberg, 2003; Watamura, Donzella, Alwin, & Gunnar, 2003).
   So far, there has been little, if any, research conducted in classrooms with young children documenting the relationship between instructional practice and physiological stress response in relation to children’s individual differences in temperament. As young children are not capable of describing their feelings/emotions about their learning experience and the observational method of stress behavior may be subjective and influenced by individual differences in expression of emotional intensity, it is important to use the improved measurement technique of neuroendocrine activity measurement in children to explore the influence of SEI and classroom DAP on children’s physiological stress responses.

Methodology
Participants
The participants were 129 kindergarteners (mean age=5.30 years) attending 11 full-day preschools/kindergartens in Taichung City, Taiwan. The 11 schools were randomly selected from a pool of 33 preschools/kindergartens. Two of the schools implemented the SEI programs. After attaining permission from the parents, the children participated in saliva sample collection and temperament assessment. To be included in the current analyses, criteria for exclusion were: children who were members of their current child care room for less than one month (n=0), were absent on any of the 2 consecutive school days (n=2), or had an illness or took medications likely to affect cortisol values during these days (n=2).

Measures and Procedures
Teachers’ assessment of the children’s internalizing disposition, measured by the approach subscale in TABC (Temperament Assessment Battery for Children) developed by Martin (1988), was used to represent a personality trait related to cortisol concentrations. Head teachers were asked to complete the teacher version of TABC, an extensive teacher report measure of temperament designed for three to eight year olds. Based on previous work by Martin (1989), the scales from the TABC were standardized and combined into six summary factors. The “approach” subscale that highly correlated with emotional tone was chosen for the focus of this study. The subscale consisted of items assessing shyness (reverse score) and interest in new things (low scores reflect withdrawal).
   The Checklist for Rating Developmentally Appropriate Practice in Kindergarten Classrooms (Charlesworth, Hart, Burts, Mosley & Fleege, 1993) was used to assess the DAP score of the classrooms. The checklist was based on the NAEYC guidelines (NAEYC, 1986) and consisted of 28 items grouped into 8 areas: Curriculum Goals, Teaching Strategies, Integrated Curriculum, Guidance of Social Emotional Development, Motivation, Parent-Teacher Relation, Evaluation, and Transitions. Each item was rated using a 5-point scale, with the most appropriate practice descriptors listed as 5 and the least appropriate descriptors listed as 1. Observers marked 5 if the item they observed was close to 100% appropriate, 4 for more appropriate than inappropriate, 3 for about equally appropriate and inappropriate, 2 for more inappropriate than appropriate, and 1 for close to 100% inappropriate. Independent rating were made by 2 professionals specialized in early childhood education. The 2 independent ratings were then averaged to create the final DAP score for each classroom. 
   Cortisol levels were measured from saliva samples collected 2 times a day for 2 consecutive school days. Samples were obtained in mid-morning (about 10:00) and mid-afternoon (about 16:00). Care was taken to collect samples from children at approximately the same time each day, and, whenever possible, a sample of at least 250 µl was collected. To collect the samples, the experimenters first demonstrated the sampling procedure for the participating children on a small group basis. The children were asked to pretend to chew a stick of gum to stimulate saliva flow and then to express the saliva into labeled test tubes through sterile straws. We also provided the children having problem with the straw method small paper cups (25c.c.) and encouraged them to spit into the cups, and the experimenters would drain the saliva into the vial. Each sample collection did not take longer than 2 min. Samples were immediately frozen until they were transferred on dry ice to our lab for cortisol analysis. The samples were stored in a –20ºC deep freezer before the assay.      
   Salivary samples were assayed using the Salimetrics TM salivary cortisol enzyme immunoassay kit (designed to capture salivary cortisol levels from 0.003 to 3.0 µg/dl), according to the manufacturer’s instructions. All samples from an individual child were assayed in the same batch whenever possible. Samples were assayed in duplicate, and the correlation between duplicate assays was r = 0.99, p <0.0001. 

Results
We first conducted preliminary analyses to examine the correlations between variables. We then use multiple regression analysis to test hypothesized relations of levels of salivary cortisol in the afternoon to the SEI, measures of classroom DAP, and children’s characteristics of internalization/externalization (the “Approach” score). In the regression analysis, we also considered levels of salivary cortisol in the morning as an independent variable to control for biological individual differences.

Preliminary Analysis
We first examined relations between the dependent variable—afternoon cortisol level (CORP) and the independent variables—whether a classroom implemented SEI (0=no, 1=yes), the DAP level of the classroom (DAP), the “Approach” score of the children (APP), and children’s morning cortisol level (CORA). Table 1 represents correlation coefficients between each of two of the above variables. As two of the independent variables—SEI and DAP are highly correlated and may cause the co-linearity problem, we put them into two different regression models and analyzed their effects on CORP separately.

Table 1. Correlations among Variables Included in the Analysis

	DAP	APP	CORA	CORP
SEI	-0.60**	0.01	-0.05	0.20*
DAP		0.11	-0.04	-0.21*
APP			-0.23**	-0.67**
CORA				0.29**

Notes. SEI=Structured English Immersion; DAP=Developmentally Appropriate Practice; APP=Approach score; CORA=morning cortisol level; CORP=afternoon cortisol level.
*p<0.05; **p<0.01.

Regression Analysis of Cortisol and SEI
In this regression analysis, we examined the relation between the afternoon cortisol measure (CORP) to SEI, APP, and CORA. Results presented in Table 2 provide regression estimates and indicate the unique effect of each variable on the dependent variable. The regression indicates that the increase of CORP is associated with the implementation of SEI, a decrease in children’s “Approach” score, and a decrease in children’s CORM.

Table2. Regression Equation Predicting Afternoon Cortisol Level (n=129), R2=0.51 (p<0.001)

	B	SE	β	Sig.
SEI	0.063**	0.018	0.213	0.001
CORA	0.210*	0.092	0.153	0.019
APP	-0.149**	0.015	-0.636	0.000

Notes. SEI=Structured English Immersion; CORA= morning cortisol level; APP=Approach score.
*p<0.05; **p<0.01.

Regression Analysis of Cortisol and DAP
In this regression analysis, we examined the relationship between the afternoon cortisol measure (CORP) to DAP, APP, and CORA. Results in Table 3 show that the increase of CORP is associated with a decrease of DAP, a decrease in children’s “Approach” score, and a decrease in children’s CORA.

Table3. Regression Equation Predicting Afternoon Cortisol Level (n=129), R2=0.49 (p<0.001)

	B	SE	β	Sig.
DAP	-0.004*	0.002	-0.132	0.043
CORA	0.202*	0.094	0.141	0.034
APP	-0.149**	0.016	-0.623	0.000

Note. SEI=Structured English Immersion; CORA= morning cortisol level; APP=Approach score.
*p<0.05; **p<0.01.

Discussion
The results of the present study suggest that both structured English immersion (SEI) and the developmental appropriateness of the classroom are associated with an afternoon increase of cortisol activity in kindergarteners. Holding children’s biological and temperamental differences constant, children in the structured English immersion program tend to exhibit a rise of cortisol in the afternoon. Similarly, holding children’s variables constant, the level of less developmental appropriateness of the classroom is associated with the rise of cortisol in the afternoon. Moreover, confidence in the findings is increased by our ability to rule out several competing explanations. Both children’s temperament and morning cortisol level were not associated with the implementation of SEI or less DAP of the classrooms. Thus, the most parsimonious interpretation of our findings was that something about SEI or DAP resulted in an afternoon increase in cortisol levels.
   However, as SEI and low DAP are highly correlated, we cannot rule out the possibility that the link between cortisol increase and SEI may reflect the effect of instructional method - the developmental inappropriateness of the instruction. As the SEI programs in Taiwan are currently developmentally inappropriate, whether children in a more developmentally appropriate SEI program would still have high stress response needs further research.
   Similar to studies conducted with children in center-based childcare in the U.S. (Tout et al., 1998; Dettling et al., 1999), child temperament was associated with an afternoon increase in cortisol. Kindergarteners who were more internalizing were more likely to exhibit the inverse pattern of normal cortisol production regardless of being in either SEI or regular programs. Therefore, it seems likely that the influence of temperament was universal and had an additive effect with SEI or DAP in producing inverse patterns of cortisol production in kindergarteners.   
   Based on the study results, our conclusions and suggestions are: 1）the Taiwanese structured English immersion classes are related to developmental inappropriateness and children’s physiological stress response, but the mechanism accounting for the stress is not clear and needs to be studied in future research, 2）classroom DAP accounts for significant variation in children’s stress behavior and thus could be considered as an important criterion in implementing young children’s English education, and 3) children’s individual differences in shyness and interest in new things are related to their stress response and need to be considered in curriculum designing and adult-child interactions.
   Since the extent of curriculum DAP is related to young children’s stress response, we recommend English teachers consider DAP principle as a reference for curriculum design and evaluation criterion of young children’s English education. Curricula for young children need to be based on what is known from research about child development and how young children learn (Bredekamp & Copple, 1997). Organizations like National Association of Education for Young Children (NAEYC) in the U. S. have advocated and documented the benefits of DAP for many years. Early childhood English teachers need to refer to the DAP principles and offer young children engaging classroom experiences that are relevant to their lives, full of hands on activities and interactive experiences, and promoting active learning and deep understanding.
   Moreover, a DAP curriculum for young children is child centered and embraces children’s individual differences. This study suggests that individual differences in temperament characteristics of young children, especially the tendency of approach or withdrawal, influence stress response and need to be especially considered by English teachers in adult-child interaction and curriculum design. Temperament differs from other learning-related individual attributes such as intelligence or motivation; it refers to how but not how well children respond to the demands in the classroom. Nevertheless, temperament differences affect the nature of children’s experiences in the classroom and contribute to the ways they approach learning tasks and their relationships with teachers and peers (Keogh, 2003).   
   Awareness of children’s temperament help educators anticipate problems and intervene when necessary. According to Keogh (2003), strategies for working with shy or children with withdraw responses include: (1) spend your time and attention equitably on these children compared with their classmates, (2) develop a daily schedule that provides consistency and familiarity to classroom activities, and alert students to upcoming changes in classroom daily routines (3) be available to help early in the assignment and signal students regarding how much time remains to complete assignments, (4) let students become involved at their own speed, especially in group activities, (5) choose student’s work partners carefully; don’t overwhelm a shy child with an active, intense, or quick-responding partner, and (6) encourage children; don’t push.    

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