4 1/2 year old with IEP for speech and language

My 4 1/2 year old has some speech delays, but i have also noticed that when you ask him questions he doesn't always understand or answer the question correctly.  For example if you ask him all the boys with green shirts on to line up, he can't put the two together that he is a boy and he has a green shirt on.  Sometimes i think he gets it, but most of the time i don't feel he is comprehending what i am asking him.  I need some things i can be doing at home to help him get up to speed with the other kids.  I don't want him to be left behind in school.  He also with have just finsihed doing something and you ask him what he has done and he will say I don't know.  Please help.

[Kevin Kennedy, Ph.D.]

It's hard to know how much of this has to do with his language difficulties (e.g., receptive language problem), how much it has to do with his overall cognitive abilities, or other aspects of information processing. The best thing would be to arrange an evaluation of his cognitive functioning. If he has an IEP, testing would have to have taken place in order to design the IEP. What did the testing reveal re: his cognitive functioning?