The Virtual Playground, along with a physical LEGO™ brick model of a playground, have been designed for use as evaluation tools. Children participants between 8 and 12 years of age have taken part and are asked to carry out the tasks which essentially involve planning the layout of the playground by modifying, resizing and placing blocks that represent the area of its various elements. These tasks require solving mathematical fraction problems, as fractions are considered to be among the most difficult topics of mathematics for primary school students. Procedure Each study is conducted with one participant at a time. The duration of the study is approximately 90 minutes for each child, whether he or she participates in one of the virtual reality conditions (experimental conditions) or the LEGO condition (control condition). In any case, prior to the activity, the participant is asked to fill out a questionnaire with math questions similar to those asked in the Key Stage 2 SAT math test. After the tests have been collected, each child is assigned to one of three groups, either the control group, or one of the two experimental groups. After the main experiment is completed, a post-test with questions similar to the pre-test is given to the participant and an informal interview is held.
Conditions condition activity interactivity immersion participants involved interactive VR (IVR) active yes yes (VR cave) 9♀, 8♂ passive VR (PVR) passive watching an avatar interact yes (VR cave) 5♀, 9♂ control (LEGOs) active no no 11♀, 8♂       25♀, 25♂ = 50 total experimental (VR) conditions: If assigned to an experimental group, the participant takes part in an activity in the virtual reality cave. In other words, the participant is immersed in a 3D re-construction of a playground in virtual reality (the Virtual Playground) and may be asked to design the playground in this 3D space. Two possibilities exist here, either: a) the participant is assigned to an “interactive VR” experience (IVR) where she actively designs the playground, having full control over the interactive features of the system or b) the participant is assigned to a “passive VR” experience (PVR), where the re-design of the playground is played out as in a video without allowing the participant to act. In any case, the task is explained to the participant through a training environment, giving her a chance to practice moving objects around in the virtual space. Overall, the experimental tasks are similar to playing with a virtual construction kit (such as LEGO®) or a computer game but do not contain fast action or violence. control condition: If assigned to the control group, the participant takes part in an activity using LEGO® bricks. The activity involves the design of a playground on a grid-like floor plan. The different coloured bricks represent the swings, slides, etc., which the participant must position in order to resize the areas that they cover according to the requirements/specifications provided. This group does not perform the task in a digital environment. Each participant is actively involved in designing the LEGO® playground; however no interactivity ("system" feedback) exists.
Scene from the exploratory experiments carried out in 2003 with three children between 7-12 y.old.	Experimental methods The experimental methods include observation, interviews and pre- and post-test questionnaires, designed in collaboration with math teachers, for different participant groups that respond to the conditions set by the experimental design. During the main experiment, the participant is asked while doing to explain her/his actions to the observer (think aloud). In all three cases, activity on paper, passive experience in VR, and activity in VR, the participants are asked to complete a post-test with questions related to fractions, similar to the pre-test. Finally, every child was interviewed about his/her experience by the researcher.
In the end, after the interview has been completed, the child receives gifts and a souvenir certificate of participation in the study.
next: results