# Selecting multiplication facts

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Purpose

The purpose of this activity is to support students in selecting an appropriate multiplication fact to solve a problem with equal sets. IIt also encourage students to begin committing multiplication facts to memory, especially those related to factors of two, five, and ten.

Achievement Objectives
NA2-1: Use simple additive strategies with whole numbers and fractions.
Required Resource Materials
• Materials to form equal sets, such as cubes, tiles, novelty counters, and play dollar coins.
• Calculators
Activity
1. Pose multiplication problems with basic facts, beginning with factors of two, ten, and five. Let students use objects or draw diagrams, if needed, to represent the problem. For example:
Kenese weaves ili (fans) to sell at Matakana market.
She makes four ili each day for five days (Monday to Friday)
How many ili does she take to the market on Saturday?

2. Discuss strategies used to work out the total number of ili. Record the strategies as equations, such as:
4 + 4 = 8, 8 + 8 = 16, 16 + 4 = 20, 5 + 5 + 5 + 5 = 20.

3. Tell students: I have a calculator. What should I enter to solve Kenese’s problem with multiplication?
Use questioning to prompt discussion.
How many days does Kenese make ili? (Enter 5 on the calculator and record it on the board)
How many ili does she make each day? (Enter x4 on the calculator and record it on the board)
How do I get an answer? (Enter = and record it on the board)
Show students the answer and complete the equation you have written (4 x 5 = 20).

4. Pose similar problems with equal groups. Encourage scaffolding and extension by grouping students. Allow the use of physical and diagrammatic models, and access to calculators. As students work, encourage them to rely more on mathematical symbols and expressions, rather than on their models. Ideally, students will progress to using multiplication calculations to solve the problems. You might also these problems as an opportunity for introducing relevant te reo Māori kupu, such as whakarea (times, of, multiply).

Good examples might be:
• Tipene catches 10 pātiki (flounder) each day to help feed his whānau.
He fishes every day of the week, unless the weather is rough.
How many pātiki does Tipene usually catch each week?
• Sophie collects All Black cards.
Her family eat a packet of Weetbix each week. Each packet contains three cards.
How many cards will Sophie have at the end of eight weeks?
• Laione walks and feeds his neighbour’s dog for 10 days.
He is paid \$4 each day. How much does he earn?
• Manu's family love kiwifruit. They eat five kiwifruit each day.
How many kiwifruit does Manu's family eat in five days?

Next steps

1. Increase the level of abstraction by progressing from using materials and diagrams to using equations to represent the problems and calculate answers.
2. Move from asking problems that involve two, five and ten as factors to problems with three, four, six, seven, eight and nine as factors. More complex problems help to ‘sell’ the efficiency of multiplication to students.
3. Build up students’ knowledge of basic multiplication facts.
4. Provide students with multiplication equations and ask them to create word problems that match.