The purpose of this article was to review movement patterns of children and how they may impact the assessment of physical activity. To accurately assess these patterns, sensitive instruments are required to detect, code, or record children’s sporadic and intermittent physical activity, also taking into consideration scientific regulations. Some of the most widely used instruments are: self-reports, direct observation, and heart monitoring. Self-reports require abstract thinking and good memory, abilities that have not yet been developed in the early years. On the other hand, direct observation and heart monitoring are more time consuming and require advanced technology, respectively. The most accepted recommendation is combining instruments to ensure greater quantity of information and more validity in the research.