Arrays help kids conceptualize multiples and factors. Three simple but powerful activities build understanding of arrays, factors, multiples, and common multiples. They can be used at the beginning of a unit on factors or as remediation. These activities are especially good for students who are having difficulty seeing patterns.
Multiples and Factors
- Use this as a starting point. In these array activities, students draw arrays for multiples of a given number. Then they consider if any additional arrays may be drawn for some of the multiples. This helps kids realize that some numbers have more factor pairs than others.
• Group Work - Give one number to each child in a group of four. Ask them to complete the task. Discussion and support from group members should be encouraged. When all members of the group, ask them to share their findings with one another.
• Individual Work - Completing all activities benefits students who are struggling with number sense. The activities may be used for tutoring and/or homework.
Exploring Related Numbers
- Each pair of students finds arrays for a set of related numbers. They cut out the arrays and create a poster to show their findings. Considering factors at this early stage in the game generates ah-ha moments. Students may see that some numbers have only one pair of factors and that some arrays are square. Let them experience this without any vocabulary or teacher talk today.
Prime, Composite, and Square Numbers
- Introduce the terms prime (exactly two factors), composite (more than two factors), and square (one array is a square - number times itself). Students walk the wall to find three square, three prime, and three composite numbers.
- Ask each group to explain how their two numbers are related. This activity supports the concept that multiples of a number share its factors.
• Multiples and Factors 1 – graph paper with directions at top asks students to draw arrays for multiples (to x 9) for two, three, four, or five
• Multiples and Factors 2 – graph paper with directions at top asks students to draw additional arrays for specific multiples of the number they were working on
• Exploring Related Numbers – teacher page with pairs of numbers to assign and graph paper to draw arrays for posters
• Prime, Composite, Square – student page asks students to find three prime, three composite, and three square numbers as they look at the posters
Are you looking for higher level factor activities? Try Finding Factors of Numbers 1-100 Cards, Sheets, and Venn Diagram
Common Core State Standard 4.OA.B.4 - Find all factor pairs for a whole number in the range 1-100. Recognize that a whole number is a multiple of each of its factors. Determine whether a given whole number in the range 1-100 is a multiple of a given one-digit number. Determine whether a given whole number in the range 1-100 is prime or composite.