Participants were drawn from three primary schools in the UK which were also participating in a parallel longitudinal study on children's writing development. Screening for the intervention, conducted at the start of the academic year, was the longitudinal study's first-time point. 532 children were screened in years 4 (aged 8–9) and 5 (aged 9–10) and were identified as SWs if, on a standardised writing measure (Progress in English 9, PiE, Kirkup, Reardon, & Sainsbury, 2006), they were in the bottom 20% of their year group from each school.
These 123 identified SWs had significantly lower writing scores on the PiE screening measure than their typically-developing peers, t (326) = 11.72, p < 0.001, d = -1.73. Parental and child consent was provided. Two further exclusionary criteria removed children who were not monolingual English language speakers and children already receiving another writing intervention. Thus, a total of 108 SWs were invited to participate in the intervention, and 76 (70.4%) received parental consent. Attrition rate was 6.6% as five participants failed to complete the intervention through withdrawal (n = 2) or disruptive behaviour (n = 3).
A total of 71 SWs, aged between 7 years 10 months to 10 years and 2 months (mean age = 9.08, SD = 7.85) completed the intervention period and were present for t1 and at least one post-test session (t2 and, or t3). There were 22 girls (10 from school 1, 7 from school 2, 5 from school 3) and 49 boys (24 from school 1, 13 from school 2, 12 from school 3) and no significant school-based differences in t1 performance were found in any measures in the study.
The assessment battery was administered in class for the PiE, 1:1 for the oral language and reading measures, or in small groups for CBM-W.
Screening and matching
Progress in English (screening)
Children completed the long form for the PiE 9 (Kirkup et al., 2006) in two blocks on consecutive days. This included narrative and non-narrative reading comprehension tasks, a story writing task, a letter-writing task, a ten-word spelling test and a grammar test. SWs were identified using the writing subtests; correlation with teacher assessment levels for writing = 0.65; reliability of the whole PiE assessment battery = 0.93.
Oral expression (t1)
Wechsler Individual Achievement Test 2nd Edition UK (WIAT-II) Oral Expression (Wechsler, 2005) subtests were administered to assess children's ability to communicate using oral language. There are three subtests for this age range, word fluency, visual passage retell and giving directions. The visual passage retell task requires children to look at tell a story based on a pictorial storyboard. Stories are marked, 0, 1 or 2, with the inclusion of specific story elements and elaboration being rewarded. Test–retest reliability = 0.86, internal reliability = 0.83–0.89. The standardised score for this scale was used as a measure of children's oral expression.
Listening comprehension (t1)
WIAT-II Listening Comprehension (Wechsler, 2005) subtests (receptive vocabulary, sentence comprehension and expressive vocabulary) were administered to assess children's ability to understand what they are hearing; reliability = 0.80. The standardised score for this scale was used as a measure of children's listening comprehension.
Single word reading (t1)
The British Ability Scales 2nd Edition (BAS-II, Elliott, Smith, & McCulloc, 1997) word reading subtest was administered to assess children's oral reading of single words, with a focus on their word decoding skills; reliability = 0.93. The measure's ability score was used to assess children's single word reading skills.
Sentence combining (t1, t2, t3)
Children completed all five items, including those designed for older children, from the WIAT-II Sentences subtest (Wechsler, 2005). They combined a series of five sentences, of gradually increasing complexity in writing. Each sentence received a score of 0, 1 or 2. Therefore, the maximum score was 10. Inter-rater reliability κ = 0.86.
Single word spelling (t1, t2, t3)
The BAS-II (Elliott et al., 1997) single word spelling subtest was administered to assess children's spelling ability. Children were asked to write the given words which were read out alone and in the context of a sentence. Words gradually increased in difficulty, ceiling and basal rules were applied, and raw scores were converted to ability scores. The test was discontinued when children passed two or fewer words in a block. Reliability = 0.91.
Writing product: curriculum-based measures of writing (CBM-W)
The outcome measure of intervention effectiveness was the CBM-W narrative writing task (Dockrell, Connelly, Walter, & Critten, 2015) undertaken by the children at all three assessment time points. Children were given five minutes to write in response to a prompt, e.g. One day I had the best weekend ever. This measure was used to establish the extent to which the interventions were effective in generalizing to writing by assessing writing productivity and accuracy.
Compositional quality (t1, t2, t3)
The text-level outcome was the compositional quality of the text; this was scored using an adaptation of the WIAT-II Holistic Scoring criteria for written expression (Wechsler, 2005). The stories were scored on a scale from 0 to 6. A low score indicates a limited attempt to respond without additional details. A high score means the text is well organised, clear, uses effective transitions and vivid vocabulary. Inter-rater reliability, κ = 0.82.
CBM-W accuracy measures (t1, t2, t3)
Accuracy measures for the CBM-W were the proportion of correct word sequences (CWS) and the proportion of words spelled correctly (WSC). A CWS is defined as a pair of consecutive words that are grammatically and syntactically correct within the context of the phrase. Interrater reliability (Cohen's Kappa) for the proportion of CWS and WSC were 0.80 and 0.90, respectively. All scoring followed the criteria set out by Dockrell et al., (2015).
CBM-W productivity measures (t1, t2, t3)
Productivity measures for the CBM-W task were the total words written (TWW), the number of complete sentences (CS) and the number of words in complete sentences (WiCS). A sentence was counted as complete if it started with a capital letter, appropriate ending punctuation, had a recognisable subject and ending punctuation. Inter-rater reliability (Cohen's Kappa) for these measures were 1.00, 0.85 and 0.86, respectively. These were scored according to the criteria developed by Dockrell et al., (2015).
CBM-W lexical diversity (t1, t2, t3)
In addition to the established scoring criteria for CBM-W, the narrative scripts' lexical diversity was analysed using the online software, Text Inspector (textinspector.com). Due to the brevity of the texts and to enable normalised gains to be calculated, Type Token Ratio (TTR) was selected as the measure of lexical diversity. TTR is calculated by dividing the number of different words (types) divided by the total number of words produced (tokens).
SWs were matched in triads across intervention groups according to their reading and oral language profiles. Children within each triad were randomly assigned to one of the three intervention groups. There were no differences between the groups (SC, MS and WLC) on the oral language and reading measures used for matching (Table 1). The descriptive statistics for these measures suggest many of the SWs also had difficulties with oral language and reading. Furthermore, comparisons between the intervention groups (SC, MS and WLC) at t1 showed they were equivalent in the key measures of WIAT 2 sentence combining (F (2, 70) = 0.63, p = 0.535), BAS spelling (F (2, 69) = 0.63, p = 0.535) and CBM compositional quality (F (2, 62) = 0.41, p = 0.665) (see Table 2).
SWs in the intervention groups were given an intervention targeting either sentence-combining or morphological spelling. Those in the WLC group continued with regular teaching for the duration of the study. The interventions ran twice a week for eight weeks, in small group sessions (4–6 children per group). Sessions lasted 25–30 min. All sessions followed a standard manualized procedure, with a script for each activity, within which it was possible to provide minor adaptations to meet the needs of the individual children. The progress of SWs in the interventions, during the intervention period, at both immediate post-test (t2) and 3-month delayed follow up (t3) was compared to a WLC group. Both interventions were administered by the first author.
Children's writing (spelling, sentence combining and text level), reading, and oral language skills were assessed at baseline (t1, mean age = 9.08 years, SD = 7.93 months). Following the completion of the intervention writing skills at the word-, sentence- and text-level (spelling, sentence combining and text production measures from the CBM-W) were re-assessed (t2, mean age = 9.12 years, SD = 7.85 months). The post-test assessment battery was repeated at a 3-month follow-up (t3, mean age = 9.05 years, SD = 7.84 months). Testing sessions were conducted over two days. At the end of the study, those in the WLC group received the SC intervention.
The SC programme was adapted from Saddler (2012). The alternative, MS intervention programme was adapted from the work of Nunes and Bryant (Nunes & Bryant, 2006; Nunes et al., 2003; Nunes, Bryant, & Olsson, 2009). Adaptations focused on developing Tier 2, small group interventions for those at risk of falling behind, which complemented classroom teaching. A brief outline of the interventions is provided below. Contact the first author for further details.
Target intervention: sentence combining
The main body of each session provided strategies, or techniques, teaching the children how to combine sentences, gradually increasing in complexity using guided practice. For the first session, the researcher explained that they were going to learn some ways to make their sentences better, children then practised sentence combining and discussed how they found the activity, they were then introduced to the first strategy of identifying important words. Each subsequent session followed a standard format of a revision of the previous session (approximately 3 min), then two or three activities focused on practising verbal and written sentence combining (lasting between 5 to 15 min). The first activity typically began with explicit modelling by the instructor, followed by guided practice. The final activity asked the children to practice the skills independently. All sessions encouraged students to provide peer feedback. Sessions finished with a summary (approximately 2 min). The final two sessions taught children to break long sentences into simple sentences and then improve them. Children were encouraged to discuss answers, provide formative feedback, and write down responses using either whiteboards or on paper.
Table 3 shows the topics for each intervention session. An example script for a whole session is presented in Fig. 1.
Alternative intervention: morphological spelling
The main body of each session used activities or games to teach children morphemes and their spellings. Children were given opportunities to receive feedback and correct their answers. The target morphemic principles, and adapted instructional materials, were taken from Nunes and Bryant (2006), who designed a series of inflectional and derivational morphological spelling interventions for 8-year-olds. In session 1, children were introduced to the structure of the intervention and told they were going to be taught some spelling rules; they discussed how they felt about spelling and discussed the different ways words can be broken down using a short spelling test. Subsequent sessions started with a revision of the previous session and included two or three activities designed to support the learning of the session's principle. An example activity, called the 'analogy task', taken from Nunes and Bryant (2006) is presented in Fig. 2, for this activity, children were asked to find the missing word. Other activities included: grouping words into word classes, identifying morphemes, finding the missing word and discussion and identification of affixes. See Table 4 for an overview of the topics for each session. To control for differences in the amount of time spent writing between the two interventions, children wrote sentences using some of the target words at the end of each session.
One researcher administered the interventions. To ensure intervention fidelity, the researcher completed checklists designed to ensure each child participated and received feedback and timed the sessions. Checklists did not differ between intervention sessions, and there was no difference in the duration of the intervention sessions, t (10) = 0.24, p = 0.817, with the SC and MS interventions lasting an average of 24.95 and 25.07 min respectively. With the exception of one session from the sentence combining intervention, where one activity was cut from the session due to time constraints, all activities from each session were successfully administered.
Two approaches were taken to control for t1 performance. First, for those measures with a maximum score (sentence combining, BAS spelling raw score, compositional quality, CBM-W accuracy measures and CBM-W Lexical Diversity), normalized gain scores were calculated, these were analyzed using two-way analyses of variance (ANOVAs). Second, for measures with no maximum score (CBM-W productivity measures of TWW, CS, and WiCS), t1 performance was entered as a covariate in a series of one-way analyses of covariance (ANCOVAs). Hedge's g was used to establish the size of the effect for each analysis; effect sizes exceeding 0.40 are reported in the text. Finally, for those measures with significant group-level differences, exploratory regression analyses were conducted to explore the role of oral language, spelling and reading skills in SWs responsiveness to the interventions.