Math Journal

We have lots of school reports, personal journal of the child, our journal etc.. Why maintain a separate journal? We can record the progress as far as our strategy goes - one reason to do it. Next it can also act as a good record for future references when we need it. Other notebooks, reports may change, places , hands etc. I feel maintaining a math journal is a good idea. But what to post in the journal? I shall discuss this in my next post.