Get ready for a seaside subtraction adventure! In Subtraction within 20 Task Cards: Collecting Seashells, students dive into a colourful beach-themed maths activity designed to develop fluency with subtraction facts up to 20. With engaging visuals and hands-on interaction, this activity invites learners to apply their mental maths strategies in a fun and purposeful way.

This set of interactive task cards helps reinforce subtraction knowledge through repeated practice and problem-solving. Each task card presents a subtraction equation and a collection of seashells, each labelled with a possible answer. Students read the equation, calculate the difference, and mark the correct answer directly on the shell. This visual process helps strengthen number sense while providing students with immediate reinforcement of their learning.

Perfect for independent maths centres, small group instruction, early finisher tasks, or home practice, this resource promotes self-direction and confidence. The seashell theme adds an element of fun, making it easy to incorporate into summer or beach-themed classroom units, or just to add something fresh to your maths block.

Key Learning Outcomes

• ✅ Build fluency in subtraction within 20
• ✅ Strengthen mental computation and number fact recall
• ✅ Develop problem-solving and decision-making skills
• ✅ Enhance number sense through visual matching tasks
• ✅ Support mathematical reasoning through hands-on engagement

What’s Included

• 34 interactive subtraction task cards
• Each card includes 1 subtraction equation and 6 possible answers displayed on seashells
• Printable instruction sheet for classroom setup and use

Materials Needed

• Printed task cards on paper or cardstock
• Laminator for durability (optional but recommended)
• Dry-erase markers or small counters for marking answers
• Storage container, zip lock bag, or envelope for easy organisation

How to Use

1. Print and cut the 34 task cards and prepare them for student use.
2. Provide students with a dry-erase marker or counters.
3. Students choose a task card and read the subtraction equation at the top.
4. They mentally subtract or use manipulatives to find the correct difference.
5. Students then place a checkmark or marker on the correct seashell showing the answer.
6. Continue with additional cards until all have been completed.

Ideas for Classroom Use

• 💡 Use in maths rotations as an independent subtraction fluency task.
• 💡 Assign as a partner activity where students check each other’s answers.
• 💡 Set up a seaside-themed maths centre with sand trays or shell props to increase engagement.
• 💡 Use as an informal formative assessment to identify subtraction strategies and fluency.
• 💡 Include in summer or ocean-themed classroom learning units for thematic integration.

Top Teacher Tips

• 💛 Laminate the cards and use whiteboard markers so they can be reused across multiple sessions.
• 💛 For students who need extra support, provide number lines or counters to aid subtraction.
• 💛 Store completed sets in clearly labelled containers for fast access during rotations.
• 💛 Extend the activity by asking students to write the subtraction sentence on a whiteboard after solving.
• 💛 Differentiate by selecting cards with simpler equations or narrowing the range to build confidence.

Subtraction within 20 Task Cards: Collecting Seashells makes mastering subtraction a beachside breeze – boosting accuracy, engagement, and number confidence one shell at a time!