Flexible bronchoscope or videoscope plays important roles in managing difficult airway. But this technique is time-consuming and very difficult to learn for novices. The investigators design a simple training simulator to help them master this technique.

In this study, residents without operational experience will be recruited. The training effect of the new simulator will be evaluated by comparison with traditional simulation teaching. Participants will receive training with the new simulator or traditional method for 1hour, and then they perform intubation with flexible videoscope in a simulated difficult airway model. The insertion time and success rate will be recorded. Last, they will complete the questionnaire.

Inclusion Criteria:

• Resident or Medical student
• Willing to participate to the study
• Consent to evaluate the measured data

Exclusion Criteria:

• experienced anesthetists