State law addresses body mass index screening or requires height AND weight measurement.
105 Code of Massachusetts Regulations 200.500 Height and Weight Measurements
Each school committee or board of health shall adopt policies and procedures to ensure that the weight and height shall be measured for each student in grades 1, 4, 7, and 10 (or, in the case of ungraded classrooms, by a student's 7th, 10th, 13th and 16th birthday), and that the student's Body Mass Index (BMI) score and corresponding percentile are calculated.
(A) Measurement of weight and height shall be done by trained school personnel or others approved by the Department for this purpose, and in accordance with guidelines of the Department. Prior notice of the screening and the benefits of the screening shall be provided to the parent or legal guardian by any reasonable means. Every effort shall be made to protect the privacy of the student during the screening. Trained school personnel or other personnel with access to the student's health information or records shall not disclose the height, weight or BMI calculations of an individual student to anyone other than the parent and/or legal guardian without written permission of the parent and/or legal guardian. The school committee or board of health may provide for additional requirements to ensure confidentiality.
(B) The student's height, weight, BMI score and corresponding percentile shall be recorded and shall be maintained in the student's school health record.
(C) The school or school district shall provide the Department annually with aggregate student BMI data including totals by grade, gender and BMI category, as specified in guidelines of the Department.
(D) Parents and legal guardians shall be provided with an opportunity to request, in writing, that their child's measurements not be taken.
Responsibilities of School Health Services
"Oversee the mandated screening programs consistent with Massachusetts General Law. Under M.G.L.c.71 s.57, these include Body Mass Index (BMI),vision, hearing and postural screenings." - I checked the law, this is for every student at request of the parent