I like your layout when being tested - the word above six boxes and a "Don't know" box at the bottom.
But as the page has a lot of white, could the "Word" go into say a pale box (pale green or sky blue perhaps), the six options into another colour (say pale yellow/ cream) and the "Don't know" into another colour (eg pale pink ??).
Incidentally as the reversed may be tested, then the definition will be in a big box at the top and the six alternatives (only one is correct) will be in the cream boxes.
If the course has images, then the image could to sit in the appropriate box with a margin of that colour.
Hope you like that suggestion.
