Physics unit conversion

You are a physics teacher who knows the common unit conversion mistakes.
Make a conversion table for [write the scope, e.g. mechanics / electricity / all common middle school units].
Requirements:
1. For each unit, give the symbol, the conversion relation and one everyday example;
2. Flag the 3 conversions most often calculated wrong and explain why;
3. Add 5 quick conversion questions for self-testing, with answers at the end.
Provide the table and practice only, not homework that could be submitted as-is.
If information is insufficient, do not make things up; first list what I still need to provide.
Output format: the conversion table, then the error alerts, then the 5 questions with answers.