Table 1. Summary of results.

Authors, country, year	Objective/focus	Population	Document type/Methodology	Key points
Nicholson, 1971; USA [10]	Original Theory of Loose Parts—explores supporting research that does not fall in the fields of art, architecture, or planning and uses this to develop a program to promote creativity in educational, recreational and environmental aspects of children's lives.	Target audience: parents and teachers	Scientific peer-reviewed journal: Landscape Architecture. No methods specified.	Found research in the fields of community interaction and involvement design along with behavioural planning and design that supports their theory. Discussed the widespread acceptance of the loose parts theory and its impact on curriculum development and environmental education, stressing that the most interesting loose parts can be found in our surroundings. Even found the theory to apply to the design of art galleries and science museums.
Vandenberg, 1981; USA [18]	To determine how quality of play and use of open-ended materials changes in children.	Children ages 4–10 (n = 45), including 24 males and 21 females	Scientific peer-reviewed journal: The Journal of Psychology Qualitatively measuring play activity with open-ended materials	Children between the ages of 4 and 10 years old were observed to see how interactions with objects changed as development progressed. It was discovered that the less developed children took part in much more simple forms of play and construction with the loose objects, while more developed children had much more complex idea of play and construction of the objects.
McLoyd, 1983; USA [19]	To observe how various aspects of children's pretend play varies with high (e.g.: dolls, tea sets etc.) vs. low-structure objects (e.g.: pipe cleaners, boxes etc.) Explores the correlation with early child development theories.	Low income, normally developing preschool children aged either 3.5 or 5 years old (n = 36)	Scientific peer-reviewed journal: Child Development. Videotaped children playing in bouts of 30 minutes, twice with low-structure and twice with high-structure objects and compared behaviours.	Younger children engaged in significantly more independent pretend play when provided with high-structure materials however the type of material did not affect cooperative play (children playing together) in either age group. High structure objects were found to elicit a larger total frequency of pretend play than low-structure objects. Findings were consistent with El'Konin's (1966) developmental views.
Drew, 2007; USA [14]	To describe the benefits of open-ended play for children.	Target audience: parents and teachers	Magazine article: Scholastic Parent and Child Magazine No methods specified	The use of open-ended materials is believed to influence many aspects of a child's life. The open-ended materials referred to include paint, clay, mud, water, blocks, and Styrofoam. It is explained how the ability to play can influence a child's ability to create a meaningful life. There is less pressure on children as there are no rules or goals to open-ended play, which also leads to no possibility of errors, and in turn offering the freedom for children to take part in play however they see fit.
Maxwell, Mitchell & Evans, 2008; USA [5]	To explore how playground equipment and loose parts affects play behaviours and provide empirical evidence that children build spaces when provided with appropriate loose parts.	Preschool aged (3–5 years) children in a child care setting (n = 32)	Scientific peer-reviewed journal: Children, Youth and Environments Observed children in a pre-, during, and post-treatment phase to explore differences In play behaviour with the inclusion of loose parts.	No previous work observed loose part effects in an outdoor environment. Play behaviours were observed before and after loose parts were introduced. Inclusion of loose parts to a playground environment increased constructive play behaviours which consequently increased dramatic play activities.
Spencer, 2008; USA [16]	Highlights the lack of un-organized and open-ended play in this generation's children.	Target audience: parents	Online journal magazine: parenting.com No methods specified	Describes how play differs for each of the 4 age groups of infants (birth-12 months) toddlers (1–3 years), preschooler's (3–5), & grade school children (5+), and provides suggestions on ways parents can support their play to encourage self-directed learning. Provides examples of common house-hold supplies that can be used as play materials.
Rockwell, 2010; USA [20]	Unpacking Imagination is a loose parts playground idea originally developed in New York	Target audience: parents	Newspaper article: The New York Times. No methods specified.	This loose parts playground intervention was developed as an attempt to diminish childhood obesity and screen time in America. Unpacking imagination features a “playground in a box”, made up of foam blocks and shapes intended to encourage children's creativity and play. The intent is that creative play be accessible to all children with this form of playgrounds.
McGonigle & Bownan-Kruhm, 2011; USA [21]	To explain how children's interactions with nature will help form more physically fit and capable individuals.	Target audience: parents	Magazine article: Natural Life Magazine No methods specified	This article argues that outdoor play can play a critical role in encouraging physical activity and increased interaction with the natural environment. It is not only motor skills that are the focus with natural play and loose parts, but other aspects such as creativity and socialization. The idea is to create environments where individuals of a range of ages are free to play and create as they wish.
Sutton, 2011. USA [17]	Explored the effects on play behaviour with the inclusion of loose parts to two outdoor learning museum exhibitions.	Observed approximately 50 visitor groups/families interacting in the museum setting.	Scientific peer-reviewed journal: Children, Youth and Environments Observed group's preference for location and children's interactions with surroundings. Caregivers completed enjoyment and assessment surveys.	Inclusion of loose parts was found to increase both the amount of time spent in the area and the parent's rating of that area. Furthermore, loose parts increased the incidence of dramatic play while improving children's engagement and understanding of the content in the area. Interestingly, children were reported to use materials that had not be intended as loose parts for play.
Marshall & Dickinson, 2012; USA [22]	To describe how to effectively equip outdoor environments for the use of open-ended materials.	Target audience: parents and teachers	Scientific peer-reviewed journal: Teaching Young Children Commentary	Outdoor play spaces offer a wide range of different opportunities when considering the use of open-ended play materials. Outdoor play may include aspects such as loose parts, music, mud, water, and many other features stemming from the indoor play environment. There is a breakdown of how to implement each of these aspects, along with what happens when they are implemented and why.
Ryan et al., 2012; USA [23]	The study aimed to look for common themes related to loose part use and collaboration between populations (children vs. teachers) and across recording techniques (drawings, written records, photos) regarding which proved to be the favorite or most enjoyable.	200+ elementary school children made up the child population and 7 teachers & 1 play specialist designer made up the adult population.	Website: Western Society for Kinesiology & Wellness Mixed methods study using the grounded theory method to examine the implementation of loose parts.	Based on the representations formed by the children and their parents, four themes were developed in the study. The themes include; pretend play, gross motor, construction, and enclosed spaces. These themes helped further develop the project as it was taking place, resulting in interaction and engagement among the children.
Mincemoyer, 2013; USA [24]	To provide an overview of existing loose parts and the idea behind the use and implementation of these objects.	Target audience: parents, teachers, and academics	Journal article: Penn State Extension, Better Kid Care No methods specified.	The idea of loose parts was originally developed by Nicholson, with the idea of the environment and creativity in mind. This article describes how loose parts can be incorporated into playground, indoor or natural settings. There is also a description of loose parts, which can include anything from balls and hoops, to more natural objects such as rocks and logs. The article determined that children preferred loose parts over more fancy, task specific toys.
Neill, 2013; USA [13]	Explores the theory of loose parts and why loose parts are important to children's play/development. Suggests different materials (natural and synthetic) that can be used as loose parts.	Target audience: parents and teachers	Curriculum Newsletter: HighScope educational research foundation No methods specified	This article describes how children prefer to play with open-ended materials, how using loose parts works to develop problem solving skills and the use of imagination in play. Also included is a description of the materials required for a loose parts seminar for teachers and details on how these parts can be adapted for use with children with special needs.
Drew & Nell, 2015; USA [8]	To demonstrate how open-ended play materials can be used and how they influence different groups of individuals.	Preschool children aged 4 and 5 years (n = 15)	Journal article: Teaching Young Children No methods specified	A workshop allowing 4- and 5-year-old children to interact with open-ended materials. It was described how this interaction influenced three groups; the children, the teachers, and the families. This article included materials such as wood blocks, rocks, boxes, fabric, foam shapes, along with many others.
Oncu, 2015; Turkey [2]	To explore children's attitudes towards unstructured play materials, were interested in looking at whether the use of recycled objects could be an adequate means of improving creative thinking.	Preschool children (4–6 years of age) from four schools (n = 126)	Scientific peer-reviewed journal: Education Journal Children were observed individually, were asked about preferred play materials and were then provided with various loose parts and asked to demonstrate as many ways as possible that they could play with each object.	Determined that most children tended to use the materials in an ordinary way and few used the materials to foster creative play. They found correlations with gender and preference for certain materials (e.g. girls tended to use the napkin more creatively than boys, while boys demonstrated a higher prevalence of creative play with the box, etc.) along with age, where older children tended to participate in more creative play overall.
Szekely, 2015; USA [15]	To highlight playground materials used in outdoor environments, and how they play a role in creative play and teaching.	Target audience: teachers	Scientific peer-reviewed journal: Art Education	In areas of Europe, adventure-style playgrounds have been around for some time now, with the intent of encouraging creative play and incorporating it in an artistic sense. It is only more recently that America has adapted a similar, yet more conservative, way of incorporating loose materials into public play spaces, with a similar intent of enhancing children's creativity.