基礎樂理教學中，教師常以鋼琴的聲音與琴鍵的呈現來輔助授課。然而，實體鋼琴往往體積龐大且價格昂貴，在空間與經費有限而無法備有實體鋼琴的環境中，教師可能會需要自備鍵盤樂器來教室授課，如此一來就會加大授課者自身的硬體負荷。「虛擬鋼琴」作為一種數位樂器，可於電腦與行動裝置上運作，儘管因觸感的限制而不適合用於鋼琴演奏的教學，若設計得宜，則可以滿足多數樂理教學的鍵盤需求。虛擬鋼琴不僅可在無法備有實體鋼琴的環境中充當替代的教學輔助樂器以外，而且在遠距教學情境中，虛擬鋼琴的聲音不需另外透過麥克風收音，琴鍵的畫面亦可透過視訊軟體中螢幕分享的功能，直接投影至遠端螢幕，因此虛擬鋼琴相較於實體鋼琴更適用於遠距教學。然而，目前的虛擬鋼琴應用程式仍未能充分滿足樂理教學演示的需求。大多數虛擬鋼琴僅提供基本的「虛擬樂器」功能，尤其在遠距教學情境下，這些應用程式常無法發出鋼琴聲音或樂理相關資訊的呈現不足。為解決這一問題，本研究設計出一款網頁虛擬鋼琴，其功能設計旨在貼合教學者在遠端環境進行樂理教學演示的需求。使用者只需開啟網頁瀏覽器，即可利用電腦鍵盤演奏，亦可選擇性地外接MIDI鍵盤來使用。本研究的虛擬鋼琴網頁不僅自帶鋼琴音源，還能顯示基礎樂理資訊，如和弦名稱、音程、音階記譜，並支援即時記譜功能，以符合遠距樂理教學演示的實際需求。本研究設計之網頁虛擬鋼琴完成後，研究者邀請30位有樂理教學經驗之音樂教學者對網頁進行使用性測試，並在受試者完成使用性實驗之後，請受試者填寫系統易用性量表(SUS)並與之進行半結構式訪談，以分析本研究之網頁虛擬鋼琴的可用性。最後，研究者將統計受試者之SUS量表分數，並結合訪談結果，針對研究成果進行探討，並提出本研究之網頁虛擬鋼琴之改良方向。根據統計分析結果，多數受試者認為本研究之網頁虛擬鋼琴具有合格的可用性，但在介面提示、記譜功能、與教學演示功能上尚有改善空間。

In basic music theory teaching, teachers often use the sound and key presentation of the piano to assist in instruction. However, physical pianos are often large and expensive. If the teaching environment, due to classroom and hardware limitations, cannot accommodate a physical piano, teachers might need to bring their own keyboard instruments to the classroom, which increases their hardware burden. As a digital instrument, the "virtual piano" can operate on computers and mobile devices. Although it may not be suitable for piano performance instruction due to tactile limitations, with proper design, it can meet the keyboard requirements of most music theory education. The virtual piano is not only useful as an alternative teaching aid in environments without physical pianos but also more suitable for distant teaching. In distant teaching situations, the sound of the virtual piano can be transmitted without the need for an additional microphone, and the keyboard display can be directly projected to a remote screen through screen sharing function in video conferencing software. However, current virtual piano applications still fall short of fully meeting the requirements for music theory teaching demonstrations. Most virtual pianos only provide basic "virtual instrument" functionality, especially in remote teaching scenarios, where these applications often fail to produce piano sound or fall short of presenting music theory-related information. To address this issue, this study designed a web-based virtual piano to better cater to the needs of educators conducting music theory teaching demonstrations in remote environments. Users can play the virtual piano using the computer keyboard or an external MIDI controller connected to the computer through USB. The web-based virtual piano developed in this study not only includes virtual instrument functionality but also displays fundamental music theory information, such as chord names, intervals, and scale notation, with real-time notation support, in order to meet the actual needs of distant music theory teaching demonstrations. After the completion of the web-based virtual piano, the researcher invited 30 music educators with experience in music theory teaching to conduct usability testing. After completing the usability experiment, participants were asked to fill out the System Usability Scale (SUS) and to participate in semi-structured interviews to evaluate the usability of the web-based virtual piano. Finally, the researcher statistically analyzed the participants' SUS scores, combined with interview results, discussed the research findings, and proposed directions for improving the web-based virtual piano developed in this study. According to the statistical analysis results, most participants believed that the web-based virtual piano developed in this study demonstrated acceptable usability. However, there were suggestions for improvement in interface, notation, and demonstration functionality.