This is not a sewing project but did lead me to create the same thing with fabric but for now I will show you the paper version. I work at a calendar company and a customer wanted a holder that she could use on her frig. After some discussion this is what I came up with.
You will Need 2 12in squares scrapbook paper 9 by 11.75 inch cardboard piece (mine was a hard file folder) adhesive (I used a glue stick and permanent Duck easy stick) Print calendar on 8.5 by 11 paper (I used Family tree maker)
Cover the cardboard piece with one sheet of the paper. I used the glue stick to cover the piece of cardboard. Fold the top and bottom to the back and secure well.
I check the size then and trimmed the sides square and cleaned the edges.
Cut the second piece of paper to 6 by 12 inches. Fold over two inches and then fold the remaining over again. Place the 2 in fold on the front side of the cardboard and center. You will not have a lot of extra paper on the ends so be careful. Add adhesive to the back side of the board where the folded paper overlaps. For good measure I added glue to between the folded paper. Glue both sides then trim the fold as shown and glue to the back.
For the bottom pockets Cut the remaining sheet into 4 by 6 strips. Fold and glue into a 2 by 6 strip with right sides out. On the folded side find the center and fold back perpendicular to form a corner. Unfold and add adhesive to the inside back portions. Lay the paper side of the card board piece on the corner piece and glue to the back.
You could secure all the back pieces with tape or if you want cover the back with another piece of paper glued securely. Apply magnets to the back.
The calendar was printed from the Family Tree maker program with family birthdays already included. I did change the top margin to 2 inches.
I think you could be very creative with this design as you could use plain paper or watercolor paper and let your kids decorate it.