I can only attest to the results:
At 8 months old her daughter was pointing at flash cards with words to identify what she wants to say. The set was limited to 10-15 words but this was helpful because she was communicating her needs and wants. At 3 years old she was sitting on her potty and reading books. Now, at 14 she fluently speaks 3 languages and is a straight A student at school.
What I learned from my sister-in-law is that you can teach a child something by simply putting the material in front of his or her eyes. This makes them remember. My sister-in-law used to glue the same math formula in every place of the house where my niece used to spend time. The math formulas and vocabulary words were in her bathroom, bedroom, in the dining room, above the TV, etc.
The walls and the doors were a mess covered with remnants of Scotch, old glue, pin holes – you name it.
My walls are pristine but I still attach formulas and vocabulary words to walls and doors. I do not use any of the permanent glueing materials, I use electrostatics. If you have ever owned static cling wall decals, or static cling stickers, or plastic film food wrap, such as Stretch-Tite, you would know what I am talking about. Glueing by applying electrostatics does not leave any traces and holds very well for quite a long period of time.
1. Any regular plastic film (you can even cut a trash bag to rectangles of the size that you need, or you can take a plastic grocery bag and cut it – Target bags work the best)
2. Electrostatic generator. Van de Graaff or electronic one would do just fine. I use electrostatic generators that come as toys, because they are portable and easy to use. I am also OK with my kids using toys. Currently I use Poly-Rollee and before that used a different toy.
3. The irregular verbs that you want your kid to remember.
All you have to do is to apply some static charge onto the film while you are holding it on the wall. I have a portable Van de Graaff with a roller that helps me charging. It comes as a toy, Poly-Rollee, and it is safe to touch. You can use any electrostatic generator.
Pardon me for the colors. I made pictures at home with my regular camera without flash, because of the glare on the film from the camera. So I had to adjust the contrast and colors. The wall is the correct color and so is the purple film, but my hand came out yellow :-).
I change the flash cards with irregular verbs every 2 days.
I have them in every room and in the bathroom.