But we've hit on a method that's working: post-it notes. It was inspired by this clip from YouTube, where the lady has square papers that she writes on.
And I thought, "I can find squares like that!" Mine are sticky on one side, but that works: We write, we scoot them around and make a couple 2-3 letter words, and then I stick them on the fridge. The plan is daily practice.
I've caught the kids looking at them a couple times. And, if nothing else, it increases the environmental exposure to Japanese that the kids are getting. Which is all to the good. It's a long trip to fluency, but baby steps get us closer!