Kindergarten, from First Principles

The shocking Duncan study finding that early math skills—not social-emotional competence—are the strongest predictor of later academic success. How executive function acts as a cognitive amplifier across 25 lifespan outcomes, and the implementation paradox where Tools of the Mind produced effect sizes ranging from 0.0 to 0.8 based purely on teacher fidelity.

Strong neurobiological foundations meet surprisingly modest measurable gains (g ≈ 0.3-0.4). Guided play as the optimal approach outperforming both free play and direct instruction, the deprivation-enrichment asymmetry, the minimum effective dose (35+ minutes), and why at-risk children benefit most.

Missing a single nap causes irreversible memory loss in habitual nappers—overnight sleep cannot compensate. Rebecca Spencer's research reveals why the hippocampal "desk" fills up faster in young children, requiring strategic timing of declarative content before naps and procedural skills after.

The unique value of symmetrical peer relationships, why conflict is developmental fuel when properly scaffolded, effect sizes from major meta-analyses (d = 0.35-0.69), the ratio question (why 7.5:1 matters), the SEL paradox, and how individual differences require differentiated support.

The intimacy paradox: close relationships create developmental magic for children but threaten sustainability. Research reveals 45-72% burnout rates, compensation as the strongest retention predictor, and Communities of Practice as the "silver bullet" for isolated practitioners.

Adherence to the curriculum matters more than which one you choose. The implementation fidelity effect, 40-70 year longitudinal data, the prepared environment paradox (structured freedom outperforms both rigid instruction and pure free play), and universal principles across frameworks.