Measures

Participants were tested individually at t1 and t2 on a range of numerical and literacy measures. For all tests, feedback was provided for practice items but not for test items, although encouragement was given by the experimenters throughout. The individual testing sessions were run by a lead experimenter and two trained research assistants, with each session lasting no longer than 40 minutes. Pre-tests were administered during a three-week period at the end of the first term of school. In the new school term, the intervention was carried out (lasting three weeks) and t2 tests were administered over three weeks immediately following training. The research assistants were blind to group membership, but the lead researcher who also administered all training sessions had knowledge of the groups.

Number measures

Arithmetic. Arithmetic was measured via an addition task. Children were given a

maximum of three minutes to solve basic addition questions, spoken aloud by the experimenter. After two practice questions, the first 13 questions were addends below 10 (e.g. 1+3, 7+2) and the final seven questions were addends above and including 10 (e.g. 5+5, 6+8). Children were encouraged to use their fingers to compute the sums. One point was awarded for each correctly written answer. The experimenter discontinued testing after five consecutive errors. A maximum of 20 marks were available.

Number identification. To assess number knowledge, children were asked to identify

numbers spoken by the experimenter. On A4 pieces of paper, children were shown a grid with four numbers; three distractors and one target. Distractor items were similar

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to the target number for example, target number 7 had distractors 706, 17 and 70. Target numbers were single, double and triple digits ranging from 2-807 and were presented in ‘Comic Sans’ size 72 font. There were three practice items and 20 test items with one point awarded for each correct answer.

Number reading. Number knowledge was also assessed via a number reading task.

Children were asked to read numbers aloud. Numbers were single, double and triple digits ranging from 1-437. All numbers were presented on A4 paper in bold ‘Calibri’ font, size 330. There were three practice items and 20 test items with one mark awarded for each.

Number writing. Children were instructed to write 15 numbers, including the numbers

1-10 and five larger numbers (range 15-100). There were 15 test items with one point awarded for each correct response. Mirror writing was allowed.

Counting. Rote counting was measured via an oral count-on task. Children were asked

to count from one and were stopped when they made a mistake, or when they reached 50. The score was the number the child counted to without mistakes (maximum score was 50).

Literacy Measures

Letter-sound knowledge. Children’s knowledge of letter sounds was assessed using a

subtest from the York Assessment for Reading Comprehension (YARC; Hulme et al., 2009). Children were presented with single letters and digraphs and asked to say aloud the sound that the letter(s) makes. One point was given for each correct response, and therefore a maximum of 17 points available.

Word reading. Examined using a subtest from the YARC, children were asked to read

single words presented to them. Words increased in difficulty and experimenter stopped testing after ten consecutive errors. One point was given for each correct answer, and therefore a maximum of 30 points available.

Rapid Automatized Naming (RAN). The letter and number subtests from the

Comprehensive Test of Phonological Processing (Wagner, Torgesen, Rashotte, & Pearson, 2013) were used to assess children’s ability to rapidly name letters and numbers. Children first practiced naming the numbers (4 8 7 2 5 3) and letters (a t s k c n) which were used in the test. Those children who were able to name the letters and

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numbers went on to take the test (note that letter names and not letter sounds were required). In both tests, 4 X 9 arrays of the letters or numbers were presented on A4 paper and children were asked to read the numbers/letters aloud as quickly as possible. If children made more than 4 errors, they were discontinued from testing (and given a score of 0). Other children progressed to Test 2 which involved the same numbers and letters presented in a different order. Total score for children who completed both tests was the combination of total time taken at Test 1 and Test 2 (seconds).

Sequences

Number sequences. Children were instructed to fill in the blanks for ten numerical

sequences (e.g. 1 __ 3 __ 5 __). Numbers ranged from 1-101, with larger numbers used in later test items. Each sequence contained two or three blank items, and a child was awarded one point for correctly filling in all blank items (maximum 10 points). Numbers were presented in Calibri size 24. There was one practice item and the experimenter discontinued after two consecutive errors.

Letter sequences. The letter sequences task was the same as the number sequence task

but used letters, rather than numbers. Sequences were generally matched across tasks (e.g. 1_3_5_ became A_C_E_) apart from the final three items which used numbers above 26 and therefore letters at the end of the alphabet were used. Letters were presented in capitals, Calibri size 24. Again, there was one practice item and ten test items with a maximum of 10 points available.