Solfege Pitch Stacks are a great visual to aide in sight singing and improvisation. This resource includes 12 Solfege Pitch Stack images, and a Power Point including all of the images.
The images are very useful when teaching solfege in a song. Just add the appropriate pitch stack to the lesson for your visual learners. You can drag and drop the images straight into Power Point, etc. and resize them to fit what you need.