See what flashcards mean with unifix cubes or legos! 1+2 means we stack 1 cube on top of 2 stacked cubes--now we have 3 cubes stacked together! 1+2=3. Lay out the flashcards and stack cubes beneath them to make each answer. Use different colored cubes for each math problem. For 1+2 we use 1 white cube and stack beneath it 2 blue cubes to give us the 3 total cubes.