Difficulties in learning to write affect a large number of children and can have a significant impact on their personal and professional future. To facilitate this learning process, develop fun, motivating and effective devices for the different skills involved in writing (motor skills, postural control, visual attention, letter recognition) is needing. Virtual Reality (VR) seems to be a promising tool for this purpose.

The SCED (Single Case Experimental Design) methodology is adapted to this study to evaluate the impact of VR on learning to write, as it allows a high level of evidence and is applicable to a heterogeneous population such as that affected by difficulties in learning to write. The study will include an original study of 3 children and 3 replications of 3 children each. In total, 12 children will be included in four different settings. This study will determine whether VR training can facilitate learning to write.

The main objective of this study is to evaluate the impact of immersive virtual reality training on handwriting using the Evaligo tool to assess static, kinematic and pressure parameters of handwriting in children aged 6 to 13 with handwriting difficulties according to a SCED methodology.

5% to 30% of children in mainstream education experience difficulties with writing acquisition. This prevalence increases among children with motor disabilities such as cerebral palsy, coordination disorders, or attention-deficit/hyperactivity disorder. Writing difficulties can significantly impact other core learning areas, as well as children's development and future (e.g., increased risk of academic failure, reduced access to higher education, lower self-esteem).

These writing difficulties are multifactorial and require individualized intervention. Fine motor skills, postural control, and visual attention-key abilities in the learning of writing-are often impaired in children with writing difficulties.

Virtual reality (VR) can be defined as the digital simulation of a virtual environment with which users can interact through their own movements. In immersive VR, users wear a head mounted display (HMD) that allows them to be fully immersed in the virtual environment.

VR has been shown to improve upper limb function and postural control in pediatric rehabilitation. It integrates several features that support motor learning, including task repetition, sensory feedback, and enhanced motivation during exercises.

Using VR training to target skills associated with writing thus appears to be relevant. Furthermore, proposing writing training through gross motor activities in VR may facilitate the consolidation of motor programs necessary for letter formation.

This engaging system could increase the amount of training, introduce variability between virtual and real-world practice, and promote the child's autonomy-all key elements for effective learning and, consequently, improved writing skills.

The following hypotheses are proposing:

• Immersive VR training will facilitate the learning of writing.
• Skills associated with writing (visual attention, fine motor skills, gross motor skills, postural control, and letter recognition) will be improved through immersive VR training.
• Motivation will be maintained throughout the intervention due to the use of VR.

A multicentre, multiple baseline SCED, following the SCRIBE recommendations will be conducting. This is a prospective design allowing intensive study of one or a few individuals with the aim of measuring their state (baseline) and the state engendered by a therapeutic intervention. It is the demonstration of 3 effects that allows us to conclude that the intervention is effective (for example: measurement of 3 effects in 3 different patients, effects corresponding to the introduction of the therapeutic intervention). This design is suitable because i/ each subject is his or her own control, which makes it possible to avoid matching difficulties (complex in our case, given the varied expected profiles of children with writing disorders) and to respect the individualised nature of the treatment, ii/ it allows the inclusion of a small number of subjects, which is well suited to a pilot study, iii/ the repeated measurements of the main outcome make it possible to ensure that the changes observed are indeed linked to the intervention. This design is adapted to the specificities of rehabilitation treatment, with an effect that lasts over time.

In this study, baseline will be randomised for each child. It will last from 2 to 6 weeks (6 to 14 sessions of repeated measurements of the primary endpoint), starting at visit 1. From this phase onwards, the children will benefit from an intervention ('control', i.e. the usual care of the child by the usual therapist) aimed at training writing (paper/pencil).

The therapeutic intervention (introduction of the VR HMD) will last 8 weeks (16 sessions of repeated measures of the primary endpoint). It will include 2 intervention sessions with the child's usual care therapist per week (during which the repeated measures of the primary endpoint will be performed by the child's therapist).

Inclusion visits (V1), visits at the start of the intervention (V2), and visits at the end of the intervention (V5) will be used to assess the skills associated with writing. V3 and V4 will evaluate the sense of presence of children just after the use of the HMD.

Inclusion Criteria:

• Age : 6-13 years
• BHK: degradation score ≥ 1 standard deviation. The BHK will be administered at the time of the inclusion visit (V1) and/or child with writing difficulties in in daily activities.
• Children benefiting or to benefit from rehabilitation care to improve handwriting skills.
• Be able to understand instructions and complete all assessments.

Exclusion Criteria:

• Contraindications to using a virtual reality HMD
• Severe visual impairment
• Facial injury
• Epilepsy
• Lack of parental and/or child consent