Background
Despite the compelling case for engaging parents in speech and language therapy, research indicates that speech and language therapists (SLTs) currently have a leading role in the goal-setting process of therapy for children with developmental language disorder (DLD). Therefore, we set out to develop a tool that aims to support the dialogue between SLTs and parents and enhance shared decision-making about children's communicative participation goals. We used co-design techniques with SLT–practitioners to include their perspectives throughout the design process. Although co-design has been used for some years in healthcare research, it is still a relatively new research methodology in the field of speech and language therapy.

Aims
To provide a detailed description of the co-design process that led to the development of a physical artefact that can support SLTs to engage parents of children with DLD in collaborative goal-setting.

Methods & Procedures
The Design Council's Double Diamond model was used to develop a tool in co-design, together with eight SLTs, who participated in all stages of the development process. Usability was tested in actual goal-setting conversations between four SLTs and 11 parents of a child with DLD resulting in stepwise improvements. In addition, usability of the first and final prototypes was tested with five usability criteria that were rated on a 10-point scale by 64 SLTs.

Outcomes & Results
The co-design process resulted in the development of a physical prototype of the tool called ‘ENGAGE’, consisting of a metal ‘tree trunk’ on which parents can stick magnetic ‘leaves’ containing potential participation goals for their child. The ‘tree’ shape represents a child's development and opportunities for growth. This first prototype received marks between 7.0 and 8.0 out of 10 on attractiveness, user-friendliness, safety, functionality and affordability. After several iterations, there were significantly higher marks for attractiveness, user-friendliness and safety in favour for the final prototype. Marks for functionality and affordability did not change significantly.

Conclusions & Implications
As researchers we usually develop pen-and-paper tools, interview protocols, apps or questionnaires to support clinical practice. Including the SLTs’ perspectives in the design process resulted in a tree-shaped physical artefact that, according to the SLTs, helps to order information and encourages and guides their dialogue with parents. We strongly advocate the inclusion of end-users in developing innovative user-centred tools for speech and language therapy and we hope that this will become widespread practice.