📐 Common Core math practice · Kindergarten

Kindergarten Math Activities — Common Core Mysteries

Kindergarten math is where numbers stop being decoration and start being tools. A cadet at this level is learning to count reliably to 100, to write numerals, to see that a teen number is really "a ten and some more," and to add and subtract small quantities without losing track. Number Cadets wraps that practice inside a mystery: to open the space station's snack locker or crack the vault's first lock, your child has to count the objects correctly, compare two numbers, or take some away and say what's left. The maths is never dressed down — it is the mechanism the story runs on. Get it right and the story moves; get it wrong and the case waits patiently while they try again.

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The six Kindergarten mysteries

🚀 Starlight Station FREE

Skill focus: Add/Sub within 10

The space station's lights went dark and the star snacks vanished! Count along to fix the station and find out who did it.

🏅 Cadet Sprout ⚡ 80 XP K.OA.A.2 K.OA.A.5

🎖️ Play free now → About this case

🔓 The Villain's Vault

Skill focus: Count, add within 10 & count by tens

The villain locked our stolen case files behind a four-layer vault. Beat four fiendish defences — laser grid, bullion balance, gear works and trip-wire alarm — to recover the files and unmask the thief.

🏅 Vault Cracker ⚡ 100 XP K.CC.B.5 K.OA.A.2 K.CC.A.1 K.CC.C.7

Launch activity → About this case

📖 The Vanished Volume

Skill focus: Numbers to 20: count, order & stack

The Grand Library's most treasured book vanished when someone secretly retyped its catalog card. Crack the card catalog, reshelve the scrambled stacks, beat the due-date desk and check the receipts to unmask the book-napper.

🏅 Book Sleuth ⚡ 100 XP K.CC.A.3 K.CC.C.7 K.OA.A.2 K.CC.B.5

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🎪 The Carnival Caper

Skill focus: Count on, make ten, tally graphs & shapes

The Golden Teddy — the carnival's famous grand prize — vanished the night before the big raffle! Crack the ticket booth's number roll, measure the evidence at the sweet stand, rebuild the prize graph and pop only the right balloons to unmask the prize-napper.

🏅 Carnival Sleuth ⚡ 100 XP K.CC.A.2 K.OA.A.3 K.MD.B.3 K.G.B.4

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🏴‍☠️ The Sunken Share

Skill focus: Count & share equal piles, +/− within 10

A chest of gold was sworn to be split into fair, equal shares — but one greedy pirate grabbed more than their share and re-buried the treasure! Split the plunder into equal shares, weigh the doubloons, crack the captain's log and fire the cannons to unmask the pirate who broke the code of fair shares.

🏅 Fair-Share Sleuth ⚡ 100 XP K.OA.A.2 K.CC.B.5 K.OA.A.5

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🌻 The Blooming Bandit

Skill focus: Teen numbers, count arrays, count on & compare heights

The prize-winning Golden Sunflower vanished the night before the Bloomtown Flower Show! Bundle the spilled seeds, replant the trampled beds, hop the bee-line trellis and rebuild the sprout charts to unmask the Blooming Bandit.

🏅 Garden Gumshoe ⚡ 100 XP K.NBT.A.1 K.CC.B.5 K.CC.A.2 K.MD.A.2

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What your child practices at Kindergarten

Across the six Kindergarten cases your cadet counts to 100 by ones and tens, counts forward from any starting number, writes numerals to 20, and answers "how many?" for objects arranged in lines, arrays and scattered piles. They compose and decompose the teen numbers into a ten plus some ones, break numbers under 10 into pairs, and build fluency adding and subtracting within 5. They also compare written numerals, compare objects by height and length, sort things into categories and count each category, and describe and compare two- and three-dimensional shapes.

Common Core standards covered at Kindergarten

Every question is tagged to one of these 12 standards, and mastery is tracked per standard for each agent. Official Common Core wording:

K.CC.A.1Count to 100 by ones and by tens.
K.CC.A.2Count forward beginning from a given number within the known sequence (instead of having to begin at 1).
K.CC.A.3Write numbers from 0 to 20. Represent a number of objects with a written numeral 0-20 (with 0 representing a count of no objects).
K.CC.B.5Count to answer "how many?" questions about as many as 20 things arranged in a line, a rectangular array, or a circle, or as many as 10 things in a scattered configuration; given a number from 1—20, count out that many objects.
K.CC.C.7Compare two numbers between 1 and 10 presented as written numerals.
K.G.B.4Analyze and compare two- and three-dimensional shapes, in different sizes and orientations, using informal language to describe their similarities, differences, parts (e.g., number of sides and vertices/"corners") and other attributes (e.g., having sides of equal length).
K.MD.A.2Directly compare two objects with a measurable attribute in common, to see which object has "more of"/"less of" the attribute, and describe the difference.
K.MD.B.3Classify objects into given categories; count the numbers of objects in each category and sort the categories by count.
K.NBT.A.1Compose and decompose numbers from 11 to 19 into ten ones and some further ones, e.g., by using objects or drawings, and record each composition or decomposition by a drawing or equation (e.g., 18 = 10 + 8); understand that these numbers are composed of ten ones and one, two, three, four, five, six, seven, eight, or nine ones.
K.OA.A.2Solve addition and subtraction word problems, and add and subtract within 10, e.g., by using objects or drawings to represent the problem.
K.OA.A.3Decompose numbers less than or equal to 10 into pairs in more than one way, e.g., by using objects or drawings, and record each decomposition by a drawing or equation (e.g., 5 = 2 + 3 and 5 = 4 + 1).
K.OA.A.5Fluently add and subtract within 5.

Questions parents and teachers ask

Is this too hard for a five-year-old?

No — every Kindergarten case is built to Kindergarten standards, with numbers kept inside the ranges the Common Core specifies (counting to 100, adding and subtracting within 10, fluency within 5). Questions are read aloud and answered by tapping, dragging and counting rather than by typing, so a child who can't yet read fluently can still play independently.

Does my child need to read to play?

Not really. The story is narrated, the instructions are spoken, and answers are given by tapping or dragging objects. Early readers manage on their own; pre-readers usually enjoy it more with an adult nearby for the story beats.

How long does one case take?

A Kindergarten case is four clue rounds of five questions — usually 10 to 15 minutes, which is about the length of a five-year-old's productive attention span. It can be paused and resumed; progress is saved.

Is it really aligned to Common Core?

Yes. Every question is tagged to a specific Kindergarten standard, and the standards each case covers are listed in full on this page with their official wording. Mastery is tracked per standard, so you can see exactly which ones your child has secured.

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