Co-design, as it applies to the fields of human-computer interaction and user-centered design, can be simplistically defined as user involvement in technology design activities. According to Berggren and Hedler, co-design is beneficial in that it provides an alternative perspective for designers when directly engaging with a given user group. While the focus of co-design was traditionally on adult end users as testers of technology, gradually the concept of a design partnership was perceived as valuable. Over time, co-design activities included children, with the recognition that it was no longer viable for adults to make decisions as to the technological needs and requirements of children. Rather it was understood that children's opinions must be integrated and factored into end products. The input of children in the design process as "active participants" particularly younger children, was previously negligible. This is generally attributed to the challenges associated with verbalization of thoughts and preferences.