Hidden array cards are a great way to reinforce a conceptual understanding of multiplication using arrays. Activity can be used with teacher directed instruction or as an independent, partner or small group activity. Includes two variations: unknown total and unknown rows.
Unknown totals: One row and one column are shown. Encourage students to use skip counting to determine the total number of dots in the array, including the ones that are hidden. Be sure to connect back to the bare number equation at the bottom when discussing rows and columns, or groups.
Example: discuss how 8 x 4 means 8 rows and 4 columns, or 8 groups of 4. They should then use the pattern of the array to skip count by 4 or 8 to find the total, or product.
Unknown rows: Only one row is shown, and students are given the total number of dots. Encourage students to use skip counting to determine how many total rows the array would have. Be sure to connect back to the bare number equation at the bottom when discussing rows and columns, or groups.
Example: discuss how (blank) x 4 = 32 means there are (blank) rows of 4, or (blank) groups of 4, with 32 being the total number of dots. They should then skip count by four until they get to the total, indicating the number of rows needed.
It is recommended to only use one “type of card” (unknown total or unknown rows) at a time, and also to stick with one factor at a time to start. Once students become fluent with one all the factors in isolation the teacher may choose to combine them all for mixed practice.
After students have figured out an answer you may allow them to check using the “full” 10 x 10 array on page three. Have students use two pieces of card stock to cover up the extra dots, leaving only their array uncovered to be counted. This is also a good opportunity to explore other strategies that weren’t discovered initially!
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