What this trial measures

• Print concept knowledgeAt pretest after enrollment and at posttest after the 12 week intervention period

  Children are administered the Preschool Word and Print Awareness (PWPA) measure (Justice et al., 2006), which examines children's knowledge of 16 basic print concepts. The PWPA has high inter-rater reliability (96% to 100%, Justice \& Ezell, 200), acceptable internal consistency (#= .7; Dobbs- Oates et al., 2015) and can reliably estimate preschoolers' print-concept knowledge (Justice et al., 2006).

• Alphabet knowledgeAt pretest after enrollment and at posttest after the 12 week intervention period

  Children are administered the Alphabet Knowledge subtest of the Phonological Awareness Literacy Screening - Preschool (PALS-PreK; Invernizzi et al., 2001). Children are presented with uppercase and lowercase letters printed in random order and receive a point for each letter named correctly. Cronbach's alphas average average .86. Inter-rater reliability is \>.96 (Invernizzi et al., 2004). The full PALS-PreK test is highly correlated with measures of reading ability (e.g., Test of Early Reading Ability, r= .67) and predicts later performance on a similar literacy measure (rs \> .53). Further, this subtest has high predictive validity in discriminating children who will later be identified as needing additional instruction (Invernizzi et al., 2001).

• Name WritingAt pretest after enrollment and at posttest after the 12 week intervention period

  Children are administered the Name Writing subtest from the PALS-PreK. In the Name Writing subtest, the child is asked to draw a picture of themselves and then write their name. They are then asked to show the assessor their name. Only the written name is scored. This subtests has high inter-rater reliability (.99). As noted above, the full test has good convergent and predictive validity (Invernizzi et al., 2001).

• Phonological AwarenessAt pretest after enrollment and at posttest after the 12 week intervention period

  Children are administered two subtests from the PALS-PreK. In the Beginning Sound Awareness subtest, the child is asked to produce the beginning sound of a word. This subtests has acceptable reliability (# = .93) and inter-rater reliability is high (.99). As noted above, the full test has good convergent and predictive validity (Invernizzi et al., 2001). The Rhyme Awareness subtest was removed in February 2026 due to feasibility concerns identified in early study data.

• Word readingAt pretest after enrollment, at posttest after the 12 week intervention period, at 3-month follow up, at 6-month follow-up, and at 12- month follow up

  At all timepoints, children are administered the Letter-Word Identification subtest of the Woodcock Johnson IV Test of Achievement (WJ IV; Schrank, McGrew \& Mather, 2014). This subtest requires children to identify or read isolated letters and words orally. This subtest has adequate internal-consistency (.94; Schrank \& Wendling, 2018). It has a high factor loading onto the Broad Reading cluster (.92; McGrew et al., 2014) which is highly correlated with other measures of reading like the Wechsler Individual Achievement Test (WIAT) Total Reading (.89; Schrank \& Wendling, 2018). It is strongly correlated with general school readiness (r = .84) as measured by the Differential Ability Scales (McGrew et al., 2014).

• SpellingAt pretest after enrollment, at posttest after the 12 week intervention period, at 3-month follow up, at 6-month follow-up, and at 12- month follow up

  At all timepoints, children are administered the Spelling subtest from the WJ IV, requiring children to draw lines, trace and write letters, and spell orally presented words. This subtest has adequate internal-consistency reliability (.92; Schrank \& Wendling, 2018) and a high factor loading onto the Broad Written Language Cluster (.87), which is highly correlated with other measures of writing like WIAT Written Expression (.77; McGrew et al., 2014). This subtest is moderately correlated (r = .69) with general school readiness as measured by the Differential Ability Scales (McGrew et al., 2014).