Flashcards are a standard study tool. They come in all shapes and designs. Let's keep it to the minimum for Sensors, though. Flashcards+ is a free app that is promises just the basics. These are like the standard index cards you find at the office supply store. Adding decks and cards is quick and easy. Need something in a pinch? Don't create a set if someone has already done this. Flashcards+ taps into Quizlet.com's database of over 8 million decks. I downloaded Really Important Basis Spanish Verbs, Italian - Food and Meals, and Muscles of the Shoulder and Arm. Notice the range of categories.
In an IEP meeting this week, we discussed a student's struggle in math due to poor memorization of math vocabulary. This prompted me to download "Geometry Vocab" as well. Maybe you'll find what you need.
This is a totally free app...no ads to support it. The only thing you pay for is audio if you want to add this feature (22 languages in multiple dialects and both genders).
As Joe Friday from Dragnet would say "All we want are the facts, ma'am." This is just what the Sensors want also - to stay focused and learning.