Subtract by Taking Away

Overview

This is lesson 3 of 5 in Tatau, Tāpiri, Tango. Students model subtraction as taking away from a starting amount, then identify how many remain. Learning is practical, oral and visual, with opportunities to use te reo Māori and explain mathematical thinking.

Learning intentions

• WALT solve subtraction problems by taking away.
• WALT identify the starting number, the amount removed and the amount left.
• WALT use counters, drawings or a number line to show subtraction.
• WALT explain how we know how many are left.

Success criteria

• I can identify the starting number.
• I can take away accurately.
• I can say or record how many are left.
• I can show my thinking with materials, a drawing or a number line.

Curriculum links

• Mathematics and Statistics — Number: exploring additive thinking and subtraction within 20.
• Mathematics and Statistics — using materials, representations and mathematical language to communicate thinking.
• Mathsteasers: developing higher-order thinking through challenge, reasoning and multiple representations.
• Mathsteasers / Alignment: connecting practical problem-solving with familiar number concepts and representations.

Lesson structure (30 minutes)

1. 0–5 min · Warm-up: count backwards. Teacher displays the counting-backwards hook and leads the class in counting backwards from 20, using a repeated movement pattern such as stepping, tapping knees or slowly opening and closing spider fingers. Students join the movement and say the numbers together, then try counting backwards from a number chosen by the teacher. Introduce tango as “take away” and, where appropriate, use tango iho for taking away and e hia ngā mea e toe ana? for “how many are left?”

2. 5–13 min · Explicit teaching: model taking away. Teacher uses counters and the subtraction modelling slides to model a story such as “There are 8 kūmara in the kete. We take away 3. How many are left?” Clearly label the starting amount, amount taken away and amount left. Move three counters away, count the remaining counters, and record 8 − 3 = 5. Repeat with a high-contrast number line, jumping backwards three times. Students act out one example with counters and turn-and-talk: “I started with __, took away __, and __ are left.”

3. 13–15 min · Explain the group tasks. Teacher shows the group-task instruction slide, models how to handle and return equipment, and reminds students that accurate counting and explaining are more important than finishing quickly. Students move to their allocated group with a partner and collect only the materials they need.

4. 15–29 min · Differentiated group practice. Teacher works first with the Emerging group, then checks each group’s strategy and questioning. Students complete the appropriate task using the subtraction practice and recording sheet where suitable.

• Emerging: Use counters to take away from sets to 10. Say the starting number, remove the stated amount, touch-count what remains, and record or dictate the answer.
• Developing: Solve subtraction facts within 20 using ten-frames and counters. Encourage students to make 10, remove counters, and explain how the ten-frame helped.
• Consolidating: Choose counters, a drawing or a number line to solve subtraction problems within 20. Students justify their strategy to a partner and show the same problem in a second representation when possible. Teacher prompts: “What was the starting number?”, “How many did you take away?”, “How can you check?”, and “Can you show it another way?”

5. 29–30 min · Review and exit response. Teacher displays the review and exit prompt and revisits the three-part language: starting number, take away, left. Students solve one oral problem, such as “There are 10 shells; 4 are taken away. How many are left?”, then show the answer with fingers, counters or a quick drawing as they leave the group.

Resources

• the subtraction lesson slide deck
• the subtraction practice and recording sheet
• Two-colour counters or small classroom objects
• Ten-frames
• High-contrast number lines to 20
• Small baskets or kete for subtraction stories
• Whiteboards, markers and pencils
• Teacher observation checklist
• Optional te reo Māori number-language cards or teacher prompts

Assessment

• Observe whether students identify the starting number before removing objects and whether they count the remainder accurately.
• Listen for the language “started with”, “took away” and “left”; note whether students can represent the same subtraction with materials, drawings or a number line.
• Use the final oral problem as an exit check. Record students who need further support with counting backwards, taking away or recording the subtraction equation.

Differentiation

• Support: Keep numbers within 10, present one problem at a time, use large high-contrast number lines and counters, and provide the sentence frame: “I started with __. I took away __. __ are left.”
• Dyslexia-friendly options: Avoid dense worksheets, use clear sans-serif print, generous spacing and strong contrast. Read each question aloud, allow students to point, build, draw or explain orally instead of writing.
• EAL and bilingual learners: Pair actions with visuals and consistent language. Accept explanations in English, te reo Māori or both, and invite students to use familiar cultural contexts such as kai, shells, harakeke leaves or objects from the local environment.
• Additional needs: Use a partner model, tactile counters and repeated routines. Reduce the number of questions while maintaining the same mathematical goal; provide movement breaks between tasks.

Extension

• Students write a subtraction story with more than one possible representation, for example counters, a drawing and a number line.
• Challenge students to find two different subtraction equations with the same answer and explain how they know both are correct.
• Invite confident students to create a subtraction story connected to sharing or collecting items in their whānau or local setting.