If it is possible to observe the iddah in the US while maintaining strict “pardah” (veiling oneself), then you should observe the iddah in the US.
Regarding your work as a kindergarten teacher, if you can take time off from your job or if your financial needs can be met without this job, then it is not permissible to continue teaching during the iddah. However, if you cannot take time off from your job and cannot afford to cover living expenses without your job, then it is permissible for you to teach during the day, making sure to return before it gets dark. Moreover, it is mandatory for you to maintain complete pardah while going out, avoid unnecessary interactions with anyone, and return home immediately after finishing work.
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دلائل:
الدر المختار: (3/ 538، ط: دار الفكر)
مات عنها في سفر) ولو في مصر (وليس بينها) وبين مصرها مدة سفر رجعت .... أو كانت في مصر) أو قرية تصلح للإقامة (تعتد ثمة) إن لم تجد محرما اتفاقا.
احکامِ میت: (234، 243 و 244، ط: ادارة الفاروق)
Allah the Almighty knows best.
Darul ifta Al-Ikhlas, Karachi.