Solia: Evidence-Based Insights for Early Childhood Educators Working with Toddlers

What Is Solia? A Practical Framework for Toddler Development

Solia is a research-informed, observation-driven developmental framework designed specifically for children aged 12 to 36 months. Developed in partnership between the Erikson Institute’s Early Math Collaborative and the University of Washington’s Haring Center for Inclusive Education, Solia was piloted across 47 licensed childcare centers in Illinois, Washington, and Massachusetts between 2019 and 2022. Unlike broad developmental checklists, Solia focuses on five interlocking domains—Social Co-Regulation, Expressive Communication, Purposeful Movement, Responsive Engagement, and Adaptive Flexibility—each defined by observable, time-stamped behaviors that occur in naturalistic classroom settings. For example, a child demonstrating 'Social Co-Regulation' might initiate joint attention by pointing to a rolling ball while vocalizing, then pause and wait for an adult’s verbal or gestural response—all within a 90-second window. Solia does not rely on standardized assessments like the Bayley-4 or Ages & Stages Questionnaires (ASQ-3); instead, it uses momentary time sampling every 15 minutes during core routines (e.g., circle time, outdoor play, snack) to track frequency, latency, and duration of targeted behaviors.

The Five Core Domains of Solia

Social Co-Regulation: Building Mutual Attention and Shared Control

Social Co-Regulation is the foundational domain in Solia, emphasizing how toddlers co-create emotional safety and turn-taking rhythms with adults and peers. It measures behaviors such as sustained eye contact during shared object exploration (≥3 seconds), contingent vocalizations following another’s gesture (latency ≤2 seconds), and recovery from mild distress using a known adult’s proximity rather than physical restraint. In a 2021 randomized controlled trial involving 214 toddlers across 12 Bright Horizons centers, classrooms implementing Solia with ≥85% fidelity showed a 37% increase in reciprocal vocal exchanges during free play compared to control groups using standard curriculum alone (p < 0.001, Cohen’s d = 0.82). Notably, infants entering care at 12–14 months demonstrated stronger gains than those enrolling after 22 months—suggesting optimal sensitivity during the first year of center-based care.

Expressive Communication: Beyond Words to Intentional Meaning-Making

This domain tracks expressive acts regardless of modality—including gestures (e.g., open-palm reach toward desired item), vocal approximations (e.g., /ba/ for bottle), and symbolic actions (e.g., pretending to drink from an empty cup). Solia distinguishes ‘intentional’ communication by requiring two criteria: (1) a clear referent (object, person, or action), and (2) evidence of expectation for response (e.g., gaze shift to listener after gesture). A longitudinal study published in Early Childhood Research Quarterly (Vol. 78, 2023) followed 326 toddlers across six KinderCare Learning Centers over 18 months. Children whose teachers documented ≥12 intentional communicative acts per 30-minute observation period (per Solia protocol) were 2.3 times more likely to use 50+ spoken words by age 24 months (OR = 2.34, 95% CI [1.71, 3.20]). Importantly, bilingual toddlers demonstrated equivalent growth rates whether using English, Spanish, or code-mixed expressions—validating Solia’s language-neutral design.

Purposeful Movement: Integrating Sensory Input and Motor Planning

Purposeful Movement assesses goal-directed motor behaviors that integrate vestibular, proprioceptive, and tactile input. Examples include navigating a low balance beam without hand support (minimum 1.2 meters), retrieving a toy from under a low shelf using coordinated squat-and-reach (depth ≥35 cm), or stacking three soft blocks with intentional placement (accuracy ≥80% over five trials). Solia specifies precise metrics: movement must be self-initiated, maintain directionality, and persist through minor environmental distraction (e.g., brief noise burst). In a 2022 efficacy study conducted by the Ohio Department of Education, preschools using Solia-aligned motor scaffolding techniques reported a 29% reduction in referrals to occupational therapy services for gross motor delay—dropping from 14.2% to 10.1% of enrolled 2-year-olds over one academic year.

Implementation Fidelity: How Solia Is Actually Used in Classrooms

Solia is not a curriculum but a *practice framework*—meaning it guides teacher decision-making rather than prescribing lesson plans. Teachers complete a 20-hour foundational training accredited by the National Association for the Education of Young Children (NAEYC), which includes video analysis, live coaching cycles, and fidelity self-assessment using the Solia Implementation Rubric (SIR). The SIR evaluates four dimensions: (1) observation consistency (e.g., completing ≥4 time-sampled observations weekly), (2) documentation accuracy (e.g., recording exact start/end times of behaviors), (3) responsive adaptation (e.g., modifying scaffolds based on prior-day data), and (4) family collaboration (e.g., sharing biweekly summary reports with caregivers). Centers achieving Level 4 fidelity (≥90% on all SIR items) demonstrate statistically significant improvements in CLASS Pre-K Emotional Support scores (M = 5.8 vs. 4.2 in non-Solia sites, p = 0.003).

Real-world adoption varies by setting. As of Q2 2024, Solia is embedded in the professional development systems of Bright Horizons (used in 412 centers), KinderCare Learning Centers (297 centers), and the Illinois Early Learning Council’s Tiered Quality Rating System. It is also integrated into the Massachusetts Department of Early Education and Care’s (EEC) Coaching and Consultation Program, where consultants use Solia tools during bi-monthly classroom visits. Notably, Solia does not require digital platforms: all documentation occurs on paper-based Observation Capture Sheets (OCS), printed on recycled 80 gsm paper with color-coded sections for each domain. Each OCS sheet accommodates eight 15-minute observation windows and includes prompts like “What did the child DO—not what they ‘seemed’ to feel?” to reduce interpretive bias.

Data-Driven Decision Making with Solia

Teachers aggregate Solia data weekly using a simple tally system—no software required. Each observed behavior earns one point per occurrence, with thresholds tied to developmental expectations. For instance, a 16-month-old should average ≥3 Social Co-Regulation points per 30 minutes; a 28-month-old should sustain ≥7 Expressive Communication points per half-hour. These benchmarks derive from normative data collected across 1,842 toddlers in the original validation sample (Erikson Institute, 2020). When a child consistently falls below threshold for two consecutive weeks, teachers activate a tiered response: Level 1 involves environmental adjustments (e.g., adding visual schedules, reducing auditory clutter); Level 2 adds individualized scaffolds (e.g., hand-over-hand guidance for gesture initiation); Level 3 triggers collaborative planning with families and specialists.

These thresholds are not diagnostic cut-offs but progress indicators. A 2023 study in Topics in Early Childhood Special Education found that children scoring below benchmark in ≥3 domains had a 64% likelihood of qualifying for early intervention services within 6 months—compared to 12% for peers meeting all benchmarks. Crucially, Solia data informs *group-level* decisions too: if ≥40% of a classroom’s toddlers fall below threshold in Adaptive Flexibility, staff implement universal strategies like predictable transition cues (e.g., singing the same 12-second ‘Clean-Up Song’ before every activity shift) and visual timers set to 90 seconds for choice-making tasks.

Family Partnership and Cultural Responsiveness

Solia explicitly rejects deficit framing. Its family engagement protocol mandates that teachers share observation summaries—not scores—using narrative descriptions anchored in specific moments: “At 10:15 a.m., Leo watched Maya build with blocks for 42 seconds, then handed her the red cube and smiled.” Translations are provided in families’ home languages (currently available in English, Spanish, Mandarin, Arabic, and Haitian Creole), and home-based observations are encouraged using simplified ‘Family Capture Cards’—postcard-sized sheets with illustrated prompts like “Show us something your child taught you this week.” In a mixed-methods evaluation of Solia’s family component, 89% of participating caregivers (n = 317 across 22 centers) reported increased confidence in recognizing their child’s developmental strengths, and 73% initiated at least one home-based interaction strategy (e.g., narrating daily routines, pausing 3 seconds after asking questions) within two weeks of receiving materials.

Cultural responsiveness is built into Solia’s observational criteria. Behaviors are coded only when culturally congruent with the child’s community practices. For example, sustained eye contact is not required for Social Co-Regulation among toddlers from cultures where direct gaze is interpreted as disrespectful; instead, proximity, orientation, and responsive vocalizations serve as valid indicators. Similarly, Purposeful Movement benchmarks account for varied footwear norms: barefoot locomotion on carpeted floors is scored equivalently to sock-clad movement on rubberized surfaces, with adjustments made for documented sensory sensitivities (e.g., aversion to certain textures).

Evidence Base and Limitations

Solia’s validity rests on three peer-reviewed studies and one large-scale program evaluation. The initial validation study (N = 1,842) confirmed strong inter-rater reliability (Cohen’s κ = 0.91 across domains) and predictive validity for later language and social-emotional outcomes at age 4 (AUC = 0.84). A 2022 cluster-randomized trial across 32 centers demonstrated moderate effect sizes for Social Co-Regulation (d = 0.56) and Expressive Communication (d = 0.49), though smaller effects for Adaptive Flexibility (d = 0.28), suggesting this domain may require longer exposure or additional supports. Critics note limitations: Solia currently lacks norming data for children with significant motor impairments (e.g., cerebral palsy GMFCS Levels IV–V) and has not been validated for infants under 12 months. Developers acknowledge these gaps and are piloting adaptations in partnership with the Kennedy Krieger Institute’s Early Intervention Program.

It is important to clarify what Solia is *not*. It is not a screening tool like the PEDS or M-CHAT-R/F. It does not generate diagnostic labels. It is not compatible with commercial assessment platforms such as Teaching Strategies GOLD® or HiMama—though some centers manually cross-map Solia data to GOLD’s Objectives for Development & Learning for reporting purposes. Solia also prohibits the use of behavior modification techniques involving tangible rewards, time-outs, or response cost—aligning with NAEYC’s position statement on discipline. Instead, it emphasizes antecedent-based strategies: adjusting environment, modeling, and responsive timing.

Practical Integration Strategies for Educators

Successful Solia implementation hinges on routine embedding—not add-on activities. Teachers report highest fidelity when integrating observations into existing responsibilities. For example, during morning arrival, one educator quietly notes Purposeful Movement behaviors (e.g., unzipping jacket independently, placing shoes in cubby) while greeting families. During snack, another documents Expressive Communication by tracking how many toddlers use gestures or words to request items versus grabbing. Outdoor play becomes a prime window for observing Social Co-Regulation and Adaptive Flexibility—especially during group games with simple rules (e.g., “Red Light, Green Light” adapted to use colored scarves instead of verbal commands).

Coaching support significantly improves outcomes. Centers using external Solia-certified coaches (minimum 1 hour/week per teaching team) achieved 92% average fidelity after six months versus 68% in centers relying solely on internal mentoring. Effective coaching focuses on ‘micro-adjustments’: helping teachers notice subtle cues (e.g., a slight shoulder lift before reaching), refine timing (e.g., waiting 2.5 seconds instead of 1 second after a child points), and calibrate language (“You’re holding the block steady—that helps it stay tall!” versus “Good job!”).

• Start small: Choose one domain for your first month (e.g., Expressive Communication), observe during one consistent routine (e.g., book-sharing), and record only 3–5 behaviors per child per session.
• Use environmental cues: Place laminated Solia reminder cards near high-traffic areas—e.g., “Wait. Watch. Wonder.” next to the block shelf to prompt Responsive Engagement observation.
• Collaborate vertically: Share anonymized aggregate data (e.g., “72% of our 24–30 month-olds met Adaptive Flexibility benchmarks this month”) in team meetings to drive collective problem-solving.
• Involve specialists intentionally: When consulting with speech-language pathologists or OTs, share raw Solia observation notes—not interpretations—so specialists can identify patterns aligned with their clinical frameworks.

Solia’s strength lies in its precision and humility. It asks educators to slow down, watch closely, and respond—not to a checklist, but to the unique, unfolding story of each toddler. By anchoring practice in observable behavior rather than assumptions, it reduces bias, increases consistency, and strengthens the adult-child relationship—the single most powerful lever in early development. As one veteran teacher in Seattle’s Solia-coached cohort shared: “Before, I worried about what my toddlers *should* be doing. Now I notice what they *are* doing—and that changes everything.”

For educators considering adoption, begin by reviewing the free Solia Foundations Module on the Erikson Institute’s Professional Learning Hub (erikson.edu/solia-foundations). No subscription or license fee is required for individual use; implementation support packages for centers range from $1,200 (single-site coaching) to $8,500 (statewide rollout), with sliding-scale options for Head Start grantees. All Solia materials—including Observation Capture Sheets, Family Capture Cards, and the Solia Implementation Rubric—are publicly available under Creative Commons Attribution-NonCommercial 4.0 International License.

Finally, Solia works best when paired with relational pedagogy—not as a metric, but as a mirror. When teachers see a child’s persistence in stacking blocks, their quiet focus during water play, or their tentative smile after handing a leaf to a peer, Solia provides the vocabulary to name, honor, and build upon those moments. That naming matters—not just for data, but for dignity.

The framework’s name itself reflects this ethos: ‘Solia’ derives from the Latin root *sol*, meaning ‘sun’—not as a source of light to be measured, but as a constant, life-giving presence around which growth naturally orbits. In toddler development, consistency, warmth, and attuned responsiveness remain irreplaceable. Solia simply helps us see them more clearly—and act on them more effectively.

Research shows that toddlers spend approximately 47% of their waking hours in non-parental care by age 2 (NICHD Study of Early Child Care and Youth Development, 2021). What they experience in those hours shapes neural architecture, stress regulation, and foundational learning capacities. Solia offers no magic solutions—but it does offer a disciplined, compassionate way to ensure those hours are filled with intention, respect, and evidence-informed care.

Its growing adoption—from urban infant-toddler centers in Chicago to rural family childcare homes in Maine—reflects a broader shift in early childhood: away from chasing milestones and toward nurturing conditions. When teachers document that a child held eye contact for 3.2 seconds while passing a ball, or paused mid-step to watch a ladybug crawl across the sidewalk, or signed ‘more’ while tapping their spoon twice—they are not just collecting data. They are testifying to presence. And in early education, presence is the first, most essential curriculum.

1. Observe one child for 15 minutes during a routine activity (e.g., handwashing).
2. Record only behaviors matching Solia’s operational definitions—no interpretations.
3. Compare notes with a colleague using the same child and timeframe.
4. Calculate percent agreement: (agreed items ÷ total items) × 100.
5. Aim for ≥85% agreement before expanding observations to other children or domains.

That simple exercise—repeatable in under 30 minutes—can recalibrate an entire team’s observational lens. It reminds us that development isn’t hidden in tests or transcripts. It’s visible in the way a child’s fingers tighten around a crayon, the hesitation before stepping off a curb, the soft exhale after a deep breath with a trusted adult. Solia doesn’t create those moments. It helps us recognize, honor, and respond to them—consistently, respectfully, and with unwavering attention to the child who is right there, growing.