Create small frames for photos using different fabrics; you’ll start adding photos from the bottom, and add new ones along the way as your child grows. (You can fill the empty frames with pretty paper until they’re ready to be filled.) Use hot glue to attach the frames along the left side of the chart, leaving the tops unglued so you can easily slip photos into the pockets.
For a dramatic view of your child’s growth, try taking pictures of them in the same pose, in the same spot, and from the same distance each time. This will emphasize the changes in your child over the years. For an example, see Watch it Grow