Riverside is publisher for CogAT. They offer some sample questions on their site. They also provide practice tests for the students if requested by the school (our district does the practice tests to ensure all of the kids are familiar with the format and types of questions). You may want to check with your school to ensure they are doing this (I think most kids need to be at least a little familiar with this type of test in todays world to have a fair chance). Building Thinking Skills 1 & 2 are long, but good skill builders for 2nd Grade CogAT if you have the time before the test.
