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