This includes 16 flashcards printed on 4 sheets of paper. Each sheet has eight boxes which will make four cards. First box has a basic unit, illustration and a question about converting units, the box next to it has the answer. I cut out the two boxes as one and fold it in half then tape/glue closed. Now I have a flashcard with answer on back. I laminated a master set for use in the classroom, and I printed out a set for each student. I made a simple red envelope and a green envelope out of construction paper for each student. Each student is quizzed and places the cards he/she got correctly in the green envelope. Any incorrect card gets put into the red envelope for further study. Page five, which you can't see in the thumbnails, has prefix flashcards (kilo, milli, centi, deci).This particular set is for the metric system and includes capacity, mass and length. I have a huge set which includes these cards, plus standard units of measure (length, volume and weight), angle measures and time.