Confusing the letters b and d is very common up to 1st grade. And yes, my first grade kiddo confuses b and d. :-) Here's a very simple activity he did today to help him in this area, using the "bed" trick. Feel free to download a copy for your child(ren) if it would be helpful!
I provided dice that I created using circle stickers and handwritten b and d letters. He rolled until he filled one side (the letters had a race-probability). I tried to watch as much as possible so that he was forming his b and d's properly. We've been spending some time relearning proper letter formation. I tend to be a stickler when it comes to that. When they form them correctly...the letters look much nicer! After he filled in the table he went onto to finger stretching the word, spelling, and writing the word under each picture. We use HWT's for our handwriting program. With this child I find that the smaller the spaces...the better the handwriting, so we are moving beyond typical 1st grade penmanship paper. I used 2 colored lines. Green for the grass and brown for the ground. He knows that above the grass is the sky. :-) This has really helped L.'s penmanship! He's made such progress since the beginning of the school year! I'm very proud of him...and even better...he sees the improvement and realizes that writing doesn't tire him as much (we are also working on proper posture :-P). He loves that he can read his own writing now!
Please remember documents from Preschool Learning and Schooling at Home are for personal use only. The website that I got this particular yak in the bed clipart is ClipArt ETC. A lovely resource for teachers (and homeschooling moms). Check them out, if you haven't done so already!