## 6 Conclusions & Future Works  
An innovative general method based on visual metaphors of learning object dimensional morphing in LMS has been introduced and applied to the task of continuous learners monitoring, obtaining an informative and usable interface, which can support the instructor throughout the learning design and verification process. Our approach can be easily integrated into existing LMSs that provide learner activity logs and appearance customisation. The visual metaphors have been implemented as Moodle themes and experimented on academic courses. Quantitative and qualitative evaluations show that the proposed approach outperforms traditional log reporting for real-time monitoring of students' engagement, using cohort dynamics and temporal analytics. Among the proposed metaphors, the _Dimensional Morphing_ prevails both in the instructors' quantitative and qualitative assessments. The main advantage of the proposed solution is in terms of usability for educators, providing intuitive visual clues instead of requiring specialised knowledge for statistical analysis and data views. Another relevant feature of our approach is that educators do not require to become acquainted with a new interface, as it uses the same visual elements, icons, and menu structure found in the existing e-learning platform. Future work includes a further tuning of the inertial factor mentioned in Section 4.3 to decide whether to change or not the term position and colour in the _Tag cloud_ and _Thermometer bar_. Methods using graphic animation can be considered to show the evolution of popularity and usage of resources over time. The formulation of other visual metaphors can be explored and tested, e.g., using a layered spatial-depth third dimension, aimed at showing in the same visual context the behaviour of different groups of users on learning objects. Further analysis on a more considerable amount of courses from different disciplines may also be useful to understand the preference for the thermometer bar better. A relevant development would also be the application of the metaphor of visual morphing and thermal maps to other web-based monitoring applications, such as portals and websites, where interface morphing is a powerful feedback tool for the site designer or manager, which conveys information about the users' engagement in terms of time spent on a page, clicks and interest in different sections. Conceptualization, A.M. and V.F. ; methodology, V.F. and A.M.; software, F.P. ; validation, V.F., F.P. and A.M.; formal analysis, V.F., A.M. and P.M.; investigation, V.F., F.P. and A.M.; resources, V.F., F.P. and A.M.; data curation, F.P. and P.M.; writing--original draft preparation, V.F. and P.M.; writing--review and editing, V.F. and A.M.; visualization, V.F., A.M. and P.M.; supervision, A.M. and V.F. ; project administration, A.M.; funding acquisition, A.M. and V.F. All authors have read and agreed to the published version of the manuscript. This research has been partially funded by the Italian P.R.I.N. e-learning project _PHRAME--Phraseological Complexity Measures_  
The authors declare the following conflict of interest: two of the authors ([PERSON] and [PERSON]) are guest editors of the special issue. The review of this article has been conducted independently by a third party editor of the journal editorial committee and anonymous reviewers. **Theoremer Bar**  
**Q.2a. ** Was the _Thermometer Bar_ tool easy to find? (not easy) \(\square\) 1. \(\square\) 2. \(\square\)3. \(\square\)4 \(\square\) 5. (extremely easy)  
**Q.2b. ** Do you consider _Thermometer Bar_ tool easy to use? (not easy) \(\square\) 1. \(\square\) 2. \(\square\)3. \(\square\)4 \(\square\) 5. (extremely easy)  
**Q.2c. ** Would you define _Thermometer Bar_ a useful tool for monitoring students activity and improving the quality of your learning objects? (not useful) \(\square\) 1. \(\square\) 2. \(\square\)3. \(\square\)4 \(\square\) 5. (extremely useful)  
**Q.2d.