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Adding and Subtracting to 20: Hop's Number Pond

Adding and Subtracting to 20: Hop's Number Pond

Learn adding and subtracting to 20, including 0, with Hop the frog: read number sentences, hop on lily pads and crack missing number puzzles.

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What you'll learn

  • Read and write number sentences using the +, − and = signs
  • The equals sign means 'is the same as': 5 = 3 + 2
  • Add one-digit and two-digit numbers to 20 by counting on
  • Subtract within 20 by counting back on a number track
  • What happens when you add or take away 0
  • Solve story problems and missing number problems like 7 =? − 9

Chapter by chapter

  1. The +, − and = signs: reading and writing number sentences

    Year 1 maths · 1

  2. Adding one-digit and two-digit numbers to 20, including 0

    Year 1 maths · 2

  3. Subtracting one-digit and two-digit numbers within 20, including 0

    Year 1 maths · 2

  4. One-step story problems with objects and pictures

    Year 1 maths · 3 Year 1 maths · 1

  5. Missing number problems like 7 = ? − 9

    Year 1 maths · 3 Year 1 maths · 1

  6. Number Sentence Challenge (10 questions)

What the chapters cover in the national curriculum in England:

  1. Year 1 maths: Read, write and interpret mathematical statements involving addition (+), subtraction (−) and equals (=) signs
  2. Year 1 maths: Add and subtract one-digit and two-digit numbers to 20, including 0
  3. Year 1 maths: Solve one-step problems that involve addition and subtraction, using concrete objects and pictorial representations, and missing number problems such as 7 = ? − 9

About this adventure

Adding and Subtracting to 20 is an interactive maths game that teaches children aged 5–7 (Year 1) to read and write number sentences with +, − and =, add and take away within 20, and solve one-step and missing number problems.

Hop the frog guides each step. Children bring ducks onto a pond, level a balance scale to see that = means 'is the same as', fill ten frames, and count on or count back along a lily-pad number track from 0 to 20. They act out story problems, choose plus or minus, and type their answers on a keypad.

Every chapter has a spoken animated introduction, hands-on teaching, practice with gentle worked examples after a mistake, and a short recap. A final 10-question challenge mixes everything together.

Questions and answers

What does the equals sign mean in maths?

The equals sign means 'is the same as': the amount on one side matches the amount on the other. That is why 3 + 2 = 5 and 5 = 3 + 2 are both true, even though the answer is not at the end.

How do you add by counting on?

To count on, start on the first number and count forwards one step for each number you are adding. For 8 + 3, start on 8 and say 9, 10, 11. Count the jumps, not the number you start on, or the answer will be one too small.

How do you solve a missing number problem like 7 = ? − 9?

Think of a story: some things were there, 9 went away and 7 are left. Put the 9 back with the 7 to find how many there were at the start, which is 16. Check it: 16 − 9 = 7.

What age is this adding and subtracting game for?

It is designed for children aged 5 to 6 in Year 1, following the national curriculum in England for addition and subtraction. Seven-year-olds who want to revise number sentences, counting on and missing numbers within 20 will also find it useful.

What is in the game and how long does it take?

The game has five chapters and a final 10-question challenge, taking about 50 minutes to play everything. Children can start any chapter from the pond map, and the Continue button takes them to the next chapter they have not finished.

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