ABSTRACT

Chapter 8 considers the evidence on the effects of P4C. Does it work? If so, in what ways? And for how long? And to what extent is the quality of implementation important? Meta-analyses are reviews of many studies that aggregate the findings. Different meta-analyses have found overall effect sizes for P4C between 0.42 and 0.58 – that is, “moderate” sizes. The Scottish study of elementary schools used cognitive tests, self-esteem tests, observational assessment of P4C classrooms and post-hoc gathering of perceptions of participants. Significant gains on cognitive abilities tests during P4C compared to controls were coupled with evidence of sustained gains two years later when the participants had changed schools. Self-esteem scores rose for P4C participants but not for controls. Observation showed more participants supported their views with reasons, they spoke more often and their utterances were longer, compared to controls. The Scottish study was replicated in Texas in middle school. A very short program of P4C had no measurable effect, but a longer program had a substantial effect. In England, a study of several elementary schools found substantial effects on attainment in reading and mathematics.