The goal of this clinical trial is to learn about (1) how speech skills can be measured and how various tests give speech therapists different types of information for children with speech sound disorder, and (2) whether changes occur in the amount of help children need when they work on easier sounds or harder sounds during treatment. The main questions this study aims to answer are: (1) what does one type of test (dynamic assessment) tell us about speech skills compared to another type of test (static assessment), and (2) does practice of easier or harder sounds show differences in progress. Participants will complete 16 sessions of speech treatment called "modified cycles treatment", and will complete several speech and language tests before, during, and after treatment by pointing to pictures, and saying sounds, words, and sentences.

The Glaspey Dynamic Assessment of Phonology (GDAP) (Glaspey, 2006; Glaspey & Stoel-Gammon, 2007) was initially developed because children with speech-sound delays make very slow progress in speech therapy and it is difficult to document change in short periods of time using traditional methods of assessment. The traditional methods rely on picture-naming tasks and the child is not given any assistance in speech productions. The lack of assistance often results in a floor effect in the documentation of change and progress. Without good documentation of change, speech-language pathologists are left uncertain about the efficacy of the treatment that they are administering. The GDAP is unique because it assesses change based on dynamic assessment; children are systematically given assistance in the production of speech sounds. When administering the GDAP, clinicians rate each sound on a 15-point ordinal scale that represents the number of cues and assistance that could be used to assist the child in sound production. Progress is documented as children need less support over time and their scores decrease. This study compares the GDAP with a traditional single-word measure. This study also has an extension to use the GDAP to select easier or harder targets during treatment, and monitor children's progress across measures over 8 weeks of modified cycles treatment. The treatment will include 16 sessions of therapy with two 50-minute sessions per week. The treatment approach that will be used is called "Cycles" and involves practicing a different speech sound each week (Rudolf & Wendt, 2014). The sounds that are practiced will be individualized to each child's needs, with harder sounds taught during four of the weeks and easier sounds taught during four of the weeks. The order will be counter-balanced across participants.

Inclusion Criteria:

• monolingual English speakers;
• scores in the mild to profound range for phonological disorder based on the Hodson Assessment of Phonological Patterns (Hodson, 2004);
• scores above 9th percentile on receptive language and cognitive abilities based on measures from the Preschool Language Scale-4 (PLS-4) (Zimmerman, Steiner, & Pond, 2002) and the Peabody Picture Vocabulary Test (PPVT) (Dunn & Dunn, 1997);
• perform adequately on a structural-functional examination adapted from the Oral and Speech Motor Control Protocol (Robbins & Klee, 1987) and Motor Speech Examination (Strand & McCauley, 1999);
• exhibit voice and fluency skills within normal limits,
• pass a hearing screening adequate for understanding speech.

Exclusion Criteria:

• will not exhibit the prime characteristics of developmental apraxia of speech and/or dysarthria

The participating children will not be aware of the targets identified as "easier" or "harder"