Why do we make an eruv tavhshilin? What is the procedure for making one? What melachos are permitted when one makes an eruv tavshilin? Sources can be found here. 

If one discovers a fly in your soup or coffee, is the soup or coffee assur? Sources can be found here. 

Is shofar blowing during Elul a mitzvah? Must one listen if one did not hear the shofar in shul? May a child blow the shofar? Sources can be found here.