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Direct observation
can be carried out with a number of reliable and 
valid tools (e.g., System for Observing Fitness Instruction Time [SOFIT], 
System for Observing Play and Leisure Activity in Youth [SOPLAY], System 
for Observing Play and Relationships in Communities [SOPARC]) devel-
oped to allow one or multiple observers to capture physical activity 
levels of youth across various settings and activities, such as physical 
education classes, recess, or leisure play in neighborhood settings (e.g., 
parks) (McKenzie et al., 1991). Observations capture information on 
sedentary (e.g., lying down or sitting), moderate-intensity (e.g., walking), 
and vigorous (e.g., running) physical activity behaviors from a sample 
of study participants. The observer can also record what activity is being 
done, where, and why. Some observation instruments also allow addi-
tional contextual information to be collected, such as social groups and 
social behavior during activities (System for Observing Children’s Activity 
and Relationships during Play [SOCARP]). Direct observation also has 
limitations, however: it is expensive, observers who collect the data must 
be trained in the use of the instruments, a sample of study participants 
rather than a census is observed, and observers must be physically pres-
ent or capture the entire area on video for later review.