🚀 Starlight Station FREE
Skill focus: Add/Sub within 20
Starlight Station lost power and the back-up snacks went missing — and it was one of the crew. Solve the puzzles to reboot the station and name the culprit.
🎖️ Play free now → About this case📐 Common Core math practice · Grade 1
First grade is the year place value arrives. A cadet stops seeing "47" as two unrelated digits and starts seeing four tens and seven ones — and that one idea quietly unlocks mental addition, comparison, and the ability to jump ten more or ten less without counting. It is also the year the equals sign stops meaning "the answer goes here" and starts meaning "these two sides balance." Number Cadets puts both ideas under pressure inside a story. Balancing the villain's bullion scale is not a worksheet about equality — it is the lock on the door, and the door does not open until the two sides genuinely balance.
🎖️ Start the free Grade 1 mystery See plans
Skill focus: Add/Sub within 20
Starlight Station lost power and the back-up snacks went missing — and it was one of the crew. Solve the puzzles to reboot the station and name the culprit.
🎖️ Play free now → About this caseSkill focus: Tens & ones, equality & compare
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.
Launch activity → About this caseSkill focus: Two-digit order, time to the half-hour
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.
Launch activity → About this caseSkill focus: Ten more, measuring, picture 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.
Launch activity → About this caseSkill focus: Halves & fourths, +/− within 20
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.
Launch activity → About this caseSkill focus: Tens & ones, count on, add on the vine & order lengths
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.
Launch activity → About this caseAcross the six Grade 1 cases your cadet counts to 120 from any starting number, reads and writes those numerals, and works with two-digit numbers as tens and ones — comparing them with >, = and <, and finding ten more or ten less mentally. They add within 100, add and subtract within 20 with fluency to 10, relate counting to addition, and test whether equations are actually true. They tell time to the hour and half-hour on analog and digital clocks, order and measure objects by length using repeated units, partition circles and rectangles into halves and fourths, sort shapes by their defining attributes, and organize data into three categories.
Every question is tagged to one of these 15 standards, and mastery is tracked per standard for each agent. Official Common Core wording:
| 1.G.A.1 | Distinguish between defining attributes (e.g., triangles are closed and three-sided) versus non-defining attributes (e.g., color, orientation, overall size); build and draw shapes to possess defining attributes. |
|---|---|
| 1.G.A.3 | Partition circles and rectangles into two and four equal shares, describe the shares using the words halves, fourths, and quarters, and use the phrases half of, fourth of, and quarter of. Describe the whole as two of, or four of the shares. Understand for these examples that decomposing into more equal shares creates smaller shares. |
| 1.MD.A.1 | Order three objects by length; compare the lengths of two objects indirectly by using a third object. |
| 1.MD.A.2 | Express the length of an object as a whole number of length units, by laying multiple copies of a shorter object (the length unit) end to end; understand that the length measurement of an object is the number of same-size length units that span it with no gaps or overlaps. |
| 1.MD.B.3 | Tell and write time in hours and half-hours using analog and digital clocks. |
| 1.MD.C.4 | Organize, represent, and interpret data with up to three categories; ask and answer questions about the total number of data points, how many in each category, and how many more or less are in one category than in another. |
| 1.NBT.A.1 | Count to 120, starting at any number less than 120. In this range, read and write numerals and represent a number of objects with a written numeral. |
| 1.NBT.B.2 | Understand that the two digits of a two-digit number represent amounts of tens and ones. |
| 1.NBT.B.3 | Compare two two-digit numbers based on meanings of the tens and ones digits, recording the results of comparisons with the symbols >, =, and <. |
| 1.NBT.C.4 | Add within 100, including adding a two-digit number and a one-digit number, and adding a two-digit number and a multiple of 10, using concrete models or drawings and strategies based on place value, properties of operations, and/or the relationship between addition and subtraction; relate the strategy to a written method and explain the reasoning used. Understand that in adding two-digit numbers, one adds tens and tens, ones and ones; and sometimes it is necessary to compose a ten. |
| 1.NBT.C.5 | Given a two-digit number, mentally find 10 more or 10 less than the number, without having to count; explain the reasoning used. |
| 1.OA.A.1 | Use addition and subtraction within 20 to solve word problems involving situations of adding to, taking from, putting together, taking apart, and comparing, with unknowns in all positions, e.g., by using objects, drawings, and equations with a symbol for the unknown number to represent the problem. |
| 1.OA.C.5 | Relate counting to addition and subtraction (e.g., by counting on 2 to add 2). |
| 1.OA.C.6 | Add and subtract within 20, demonstrating fluency for addition and subtraction within 10. Use strategies such as counting on; making ten; decomposing a number leading to a ten; using the relationship between addition and subtraction; and creating equivalent but easier or known sums. |
| 1.OA.D.7 | Understand the meaning of the equal sign, and determine if equations involving addition and subtraction are true or false. |
Two big ones: numbers get bigger (to 120, and adding within 100), and place value becomes explicit — tens and ones as separate, meaningful columns. Time and fractions also appear for the first time, at the half-hour and half/quarter level.
Yes, and they should. Every case is drawn fresh from question pools each time, so the story is familiar but the maths is new. Replaying is how fluency gets built without it feeling like drilling.
Yes. Grades are chosen, not locked. If a Grade 1 cadet is comfortable, move them up; the same six mysteries exist at every grade, so they keep the story they like and get harder maths.
Yes. Every question is tagged to a specific Grade 1 standard, listed in full on this page with official wording, and mastery is tracked per standard.