Find the Missing Number

About this activity

Every equation is a gap in a path beside a stream, and every number card is a plank exactly as long as its number. The child taps an equation’s signpost, then a plank: it unfolds into the gap square by square. Only the number that makes the equation true fits. A plank that is too short falls into the water, and one that is too long sticks out past the far bank.

Each path has four gaps, and the missing number sits in a different place in each: the number added first, the number added second, the number taken away, the starting number, the total or the difference. A missing starting number or total is a slot under the road. The tray holds five planks: the four answers and one that fits nowhere — usually a typical mistake, such as adding the two numbers you see or subtracting the wrong way round. When all four planks fit, the animal crosses to the flag.

In the “Numbers only” setting the path shows no squares until a plank is laid, so the child works the number out first. Aligned to Common Core 1.OA.D.8. No timer and no score.

What's inside this activity

• Designed for Grade 1 learners (ages about 6–7)
• Common Core strand: Operations & Algebraic Thinking
• Aligned to Common Core standard 1.OA.D.8

How to play

Tap an equation’s signpost to choose its gap. The next open gap is already chosen for you.

Tap a plank. If its number is right, it fits the gap; if not, it falls in or sticks out and goes back to the tray.

After two wrong planks in the same gap, its squares are numbered so you can count them.

Tap a signpost with a plank in it to take the plank out again.

In the settings, choose the numbers (within 10 or within 20) and the path (with squares or numbers only).

What your child practices

• Finding the missing number in any position: an addend, the number taken away, the starting number, the total or the difference
• Seeing every equation as two parts and a whole
• Checking an answer by fitting it: too short, too long or just right
• Spotting the typical mistakes: adding the numbers you see, or subtracting the wrong way round

Learning goals

Find the unknown number in an addition or subtraction equation, wherever it is

Understand that the two parts of an equation make its whole

Use addition to solve a subtraction with a missing number

Check an answer instead of guessing