Display the multiplication fact grid and give the students a few minutes to discuss in pairs any patterns they notice.
List students' ideas on the board (e.g. the first row and column in the unshaded section are all zeros, the second row and column are counting by ones, each column has a corresponding row that is the same).
Ask: Why do you think the numbers in the first row and column all end is zero? What does this mean?
Encourage students to use models and everyday examples to develop a convincing reason.
You can download and view the Multiplying by Zero slide show.
Explore the second column and row (counting by ones), and the square numbers (1, 4, 9, 16, 25 etc.) in a similar manner.
Some teaching tips about possible patterns can be seen in the following slide show.
You can download and view the Noticing Patterns slide presentation.