Four-book challenges:
- mini centre cross
- mini centre x
- four corners
Four- or five-book challenges:
- any row, column or diagonal
Eight-book challenges:
- large centre cross
- inner square
- large X
- capital T (since it’s Mrs. T.’s challenge)
12-book challenge:
- diagonal stripes
16-book challenge:
- outer border
24-book challenge:
- the whole card