If the children are Canadian citizen, there is a permit called TN which they can obtain to work in the US. You can find more information on Canadian immigration website.
Originally Posted by rbakker
04/11/2001 - I-130 mailed
05/22/2002 - I-130 approved
11/18/2004 - Wife became USC
11/19/2004 – i-485 filed through DORA.
11/30/2004 – FP
11/22/2005 - Applied for Renewal EAD
12/16/2005 - Biometrics for Renewal EAD
02/23/2006 - Received Renewal EAD
10/31/2006 - Applied for Renewal EAD
11/25/2006 - Biometrics for Renewal EAD
12/01/2006 - Received Welcome Letter Mailed Email from USCIS
12/05/2009 - Filed N-400
01/05/2010 - Biometrics
02/16/2010 - N-400 Interview - Approved