Table 1

Project measures

Measure	Construct	Description	Time (min)	Time point
Measure	Construct	Description	Time (min)	Baseline	6 months*	12 months*
Screening measure
Wheldall Assessment of Reading Lists24	Reading	The test asks the child to read three lists of 100 words for 60 s each. The mean numbers of correct responses on each of the three subtests are used to calculate the child’s score. A cut-off of 17 indicates the child is in the bottom 25th percentile of readers.	5	♦
Primary outcome
York Assessment of Reading for Comprehension-Passage Reading (YARC-PR)26	Reading ability	The YARC-PR is an individually administered paper-based assessment of early reading skills in children aged 4–7 or older children that is used to identify reading difficulties. The YARC-PR provides three subtest scores: (1) accuracy, (2) reading rate and (3) comprehension. The test produces raw scores for each subtest in the passage reading component which can be converted to a standard score (mean=100, SD=15), percentile rank and age equivalents. The measure assesses the student using one of two parallel tests of graded passages (A and B) with eight accompanying comprehension questions. The assessment is conducted individually by a trained research assistant and takes about 10 min per student.	15	♦†	♦	♦
Secondary outcomes
York Assessment of Reading for Comprehension-Early Reading30	Reading skills	Assesses phonological awareness skills, alphabetic knowledge and individual word reading and comprises four subtests, which are (1) letter sound knowledge, (2) early word recognition, (3) sound deletion and (4) sound Isolation. The measure is individually administered and takes approximately 15 min to complete per child. The test provides raw scores for each subtest in the early reading component which can be converted to a standard score (mean=100, SD=15), percentile rank and age equivalents. A phoneme awareness composite can also be calculated by the combining of scores on the sound isolation and sound deletion subtests.	10	♦	♦	♦
Castles and Coltheart Test 231	Single word reading	Assesses the functioning of the key processes in single word reading: sounding out ability and whole word recognition ability. The full test consists of 40 regular words, 40 irregular words and 40 non-words, which are presented one at a time, in mixed order, and with gradually increasing difficulty. The measure has been validated in 6–8 year-old children. Both raw scores and standardised scores are available for each subscale.	3	♦	♦	♦
Confounders
Children’s Test of Nonword Repetition32	Phonological memory	Assesses the ability to access lexical and phonological information rapidly and efficiently. Non-word reading provides a direct measure of verbal working memory, which is often compromised among children with reading and literacy-related impairments. It has been normed for children from 5 to 18 years (mean=100, SD=15).	2	♦
Rapid automatised naming33	Processing speed	Assesses the capacity to automatically and efficiently retrieve linguistic or non-linguistic information. Rapid automatic naming provides information about children’s ability to rapidly retrieve phonological and/or orthographic representations of words. This is predictive of the ability to read fluently and with automaticity. The measure takes approximately 3 min to administer per child and has been standardised and validated for children between 4 and 8 years who are attending mainstream schools (mean=100, SD=15).	3	♦

*After randomisation.
†Conducted by classroom teacher.