Programs that Work
Know Your Body
Healthy and Safe Children
Youths not using alcohol, tobacco, or illegal drugs
Age of Child
Middle Childhood (9-12)
Type of Setting
Type of Service
Type of Outcome Addressed
Substance Use and Dependence
Evidence Level (What does this mean?)
Know Your Body (KYB), as evaluated and reported here, was a comprehensive, skills-based health promotion program that targeted students in the fourth to ninth grades. The goal of KYB was to teach students the necessary knowledge, attitudes, skills, and experience to practice positive health behaviors and reduce their risk of future illness. The program has since been modified to target kindergarten through sixth-grade students, but the modified program has not been evaluated and the information reported here is only for the evaluated, fourth-grade to ninth-grade program.
The KYB curriculum focused on voluntary behavioral changes in the areas of cigarette smoking, physical fitness, and diet, and was taught by the regular classroom teacher for approximately two hours per week throughout the school year. The cigarette smoking prevention component taught students the skills necessary to resist pressures to smoke cigarettes, while the physical fitness component helped students to begin a regular program of endurance exercise designed to improve cardiovascular fitness. The nutritional component of the curriculum focused on encouraging students to adopt the American Heart Association’s "prudent diet," which consists of decreasing the consumption of total and saturated fat, cholesterol, sodium, and refined sugar; increasing the consumption of complex carbohydrates and fiber; increasing the consumption ratio of polyunsaturated fat to saturated fat; and maintaining an ideal body weight.
As evaluated, the program targeted fourth-grade to ninth-grade students. Currently the program targets elementary school students in grades K-6.
The Know Your Body program has been evaluated in four major studies, all of which focused on the effects of the program on chronic disease, cardiovascular risks, and cancer-related risk factors, including smoking. Only smoking-related results from two major studies are reported here because the other studies of KYB experienced methodological problems that prevented their inclusion. A brief description of the two evaluations follows:
Bronx, New York (Walter et al., 1985, Walter et al., 1988): A total of 1,563 4th-grade students in 22 elementary schools from a single school district were randomly assigned to either a treatment group (in 14 schools as part of the KYB program) or to a control group (non-participants in 8 schools). The school district was located in an inner-city urban district in the New York City borough of the Bronx. The intervention program lasted a total of five years, from the fourth to eighth grades. Participants were assessed one year after the start of the program and again at five-years following completion of the intervention program. After one year, 1,115 students remained in the sample (an attrition rate of 29 percent), and 1,036 students remained after five years (a 34-percent attrition rate). The outcome measure studied was students’ levels of a biochemical marker (serum thiocyanate) that indicates cigarette smoking.
Westchester County, New York (Walter et al., 1986; Walter et al., 1987; Walter et al., 1988; Walter et al., 1989): 1,105 fourth-grade students from 15 elementary schools in four school districts were randomly assigned to a treatment group (in 8 schools as part of the KYB program) or a control group (non-participants in 7 schools). The intervention lasted six years, while the students completed grades 4 through 9. Westchester County is a predominantly white, suburban, middle- to upper-middle-class area in proximity to New York City. One-, three-, five, and six-year follow-up assessments (from the beginning of the study) were conducted on this sample of children. The attrition rate at the one-year follow-up was 21 percent, 18 percent at the three-year follow-up, 20 percent at the five-year follow-up, and 35 percent at the six-year follow-up. The study outcome measures of interest were students’ levels of serum thiocyanate and their levels of saliva cotinine (another biomarker for cigarette smoking). The authors reported no significant differences between those students who left the study and those who completed it.
Key Evaluation Findings
The Bronx study (Walter et al., 1985; Walter et al., 1988) found:
- Significant differences between the intervention and control groups at the one-year follow-up. From baseline to follow-up, the average level of serum thiocyanate detected in KYB students decreased by 5 percent, while levels of serum thiocyanate for control group students increased by 9 percent.
- No significant differences between the intervention and control group at the five-year follow-up.
- Significant differences between the intervention group and control students at the one-year follow-up, with intervention students demonstrating significantly lower levels of serum thiocyanate than control students. From baseline to follow-up, serum thiocyanate levels for the intervention group increased by 2 percent, while the control group showed an increase of 15 percent.
- No statistically significant differences between the intervention and control groups at the three-year or five-year follow-up.
- At the six-year follow-up, when the students were in the ninth grade, the rate of cigarette smoking as determined by thiocyanate levels was 73 percent less among intervention group students than among control group students. While 13.1 percent of participants in the control group were biochemically classified as current cigarette smokers, only 3.5 percent of participants in the KYB group were classified as such.
- When analyzed separately for gender, the intervention was found to be effective only for male students.
Public and private elementary schools
Developmental funding for the project included the American Health Foundation; the National Heart, Lung, and Blood Institute; the National Cancer Institute; and the W.K. Kellogg Foundation.
Program materials for KYB were specific to each grade, and included teacher guides, student workbooks and worksheets, videotapes, posters, and calendars.
The curriculum was developed according to the principles of social learning theory, and each activity was designed to incorporate learning strategies to encourage behavior change, including modeling of desired behaviors, behavioral rehearsal, goal specification, feedback of results, and positive reinforcement for favorable behavior change.
Teachers were trained in the KYB curriculum in three half-day teacher workshops. Adherence to the curriculum and teaching protocols was ascertained through teacher monitoring, which included documentation of attendance at training workshops and the number of classroom lessons taught, along with intermittent classroom visits by the research staff.
Issues to Consider
This program received a "promising" rating. The evaluations used a randomized experimental design and longitudinal follow-up, and participants in the majority of the studies experienced significantly reduced levels of smoking (as measured by serum thiocyanate levels) compared with the control group. However, findings were mixed at different evaluation times between the two major studies.
While serum thiocyanate levels are one indicator of cigarette smoking, there is a concern that this measure might not fully capture experimental smoking. None of the evaluations used any other non-biochemical indicator of smoking, e.g., self-reported smoking behavior, so it is not possible to check on the validity of serum thiocyanate for measuring actual smoking levels. In addition, one longitudinal study found the program to be more effective with males than with females.
Bronx, New York; Los Angeles, California; Santa Monica, California; Washington, D.C.; Westchester County, New York
Kendall Hunt Publishing Company
4050 Westmark Drive
P.O. Box 1840
Dubuque, Iowa 52004-1840
A description of current K-6 program components for each grade level, and order forms for program materials, are available on the Kendall Hunt website: http://kendallhunt.com/kyb.
Taggart, Virginia S., Patricia J. Bush, Alan E. Zuckerman, and Patricia K. Theiss, "A Process Evaluation of the District of Columbia ‘Know Your Body’ Project,"
Journal of School Health,
Vol. 60, No. 2, 1990, pp. 60-66.
Walter, Heather J., Albert Hofman, Linda T. Barrett, Patricia A. Connelly, Kathryn L. Kost, Ellen H. Walk, and Rebecca Patterson, "Primary Prevention of Cardiovascular Disease Among Children: Three-Year Results of a Randomized Intervention Trial," in B. Hetzel and G. S. Berenson, eds., Cardiovascular Risk Factors in Childhood: Epidemiology and Prevention, New York, NY: Elsevier Science Publishers B.V. (Biomedical Division), 1987.
Walter, Heather J., Albert Hofman, Patricia A. Connelly, Linda T. Barrett, and Kathryn L. Kost, "Coronary Heart Disease Prevention in Childhood: One-Year Results of a Randomized Intervention Study," American Journal of Preventive Medicine, Vol. 2, No. 4, 1986, pp. 239-245.
Walter, Heather J., Albert Hofman, Patricia A. Connelly, Linda T. Barrett, and Kathryn L. Kost, "Primary Prevention of Chronic Disease in Childhood: Changes in Risk Factors After One Year of Intervention," American Journal of Epidemiology, Vol. 122, No. 5, 1985, pp. 772-781.
Walter, Heather J., Albert Hofman, Roger D. Vaughan, and Ernst L. Wynder, "Modification of Risk Factors for Coronary Heart Disease," The New England Journal of Medicine, Vol. 318, No. 17, 1988, pp. 1093-1100.
Walter, Heather J., Roger D. Vaughan, Ernst L. Wynder, "Primary Prevention of Cancer Among Children: Changes in Cigarette Smoking and Diet after Six Years of Intervention," Journal of the National Cancer Institute, Vol. 81, No. 13, 1989, pp. 995-999.