This displays a sheet that asks students to identify clues that will help them decide whether addition, subtraction or both are needed to solve each problem.

• The calculations involved in these problems are relatively easy so that students can focus on the process. You could also remind students that sometimes temporarily substituting single digit numbers for larger numbers in problems can help in this decision-making process.
• Encourage students to find as many clues as they can. These clues should be derived from the meaning of the problem as well as the vocabulary.
• Page 2 of this teacher resource sheet requires students to use addition and subtraction to solve the problem and answer the question.
• These examples could also be used as examples to remind students of the problem-solving process before they begin to solve the problems in Activity 1.

This displays a sheet that asks students to identify clues that will help them decide when to use multiplication and when to divide when both are needed to solve a problem.

• The calculations involved in these problems are relatively easy so that students can focus on the process.
• Encourage students to find as many clues as they can. These clues should be derived from the meaning of the problem as well as the vocabulary.

This displays the Getting started activity on page 147 of the Student Resource Book.

• While key words such as ‘altogether’ and ‘left’ may provide clues about the operation required, they may also mislead. It is helpful for students to ask whether groups are of equal size, are being combined or being separated, or are being compared so the problem is asking for the difference between groups. Often drawing a diagram, or modelling a problem by acting or using materials, helps students to decide.

This displays four problems. Students are asked to match each problem to a diagram and then write an appropriate equation and solve the problem.

• These diagrams can be useful for students to identify whether the numbers in a word problem represent the whole or part in an equation.
• Problem 1 could be solved by either addition or subtraction as it asks the student to find the difference between two amounts.
• You could use the interactive modelling tool which can be used to model any of the problems in this chapter or to create further problems. This tool will be most helpful for those who are already familiar with ‘Thinking blocks’.

This displays two secret number problems. Students are asked to begin with the answer and use the inverse of each operation to find the original ‘secret’ number.

• This sheet reinforces the important concept of the operations which ‘undo’ each other. Students can explore these problems by beginning with the answer and using the inverse operation to work their way back to the starting point.
• Students could use materials like counters or a happy face array to help them calculate.
• Encourage students to create as well as solve these puzzles. The extra task for this section, “I know the number you’re thinking of” provides an additional puzzle that involves all four operations.