Instrument
The ToP is an observational assessment administered by an unobtrusive rater during a 15-min sample of free play in a familiar environment with familiar peers. Playfulness is rated on 30 items, using a 4-point (0–3) scale that reflects extent, intensity, or skill. The ToP has been shown in numerous studies to have adequate evidence for reliability and validity (e.g., Bundy et al., 2001).