Barbara and Kahu are building domino stack houses and made a table to show the relationship between the number of storeys and dominoes needed. The table shows that for 1 storey you need 2 dominoes, for 2 storeys you need 4 dominoes, and for 3 storeys you need 8 dominoes. They are trying to find the rule for this relationship and use it to determine how many dominoes would be needed for houses of different heights.