I think you could also have multiple pipe cleaners coming from one number and students have to show multiple ways to add numbers to get to that number. Counting with pipe cleaners and beads. Great for fine motor development too.
Counting Activity Using a Geoboard. Here is something every teacher has in their classroom and can make on your own. So simple and a GREAT idea. Easy to go back and check student work and collect IEP data. Read more about this great idea and some others at: http://www.aneverydaystory.com/2014/06/03/number-letter-sequencing/