🚀 Free Grade 4 math mystery · instant · no sign-up
Someone tampered with the navigation and reactor logs, and the spare fuel cells are gone. Fourth graders run the real numbers — multi-digit addition, multiplication, and division — to set the station right and unmask the saboteur. It is completely free, needs no account, and works on any school computer.
🕵️ Start the Mystery — free All grades
Back-to-school special: everything is FREE until August 31 — all the Grade 4 mysteries, 35+ cases in all, with a free account. No card needed. For parents & teachers: unlock all the Grade 4 mysteries — Family $29/yr · Classroom $49/yr, per-standard Common Core progress tracking included.
🎉 Claim free access →⭐ Unlock everything →Four clue stations, each a different interactive challenge — then line up the suspects and name the culprit. About 15–20 minutes, replayable with fresh clues every time.
The others are members-only cases — same detective format, 6 different worlds, each with its own mechanics and its own Grade 4 math:
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.
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.
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.
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.
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.
The night before the big Toy Fair, someone jammed the great toy factory's machines and hid its masterpiece — the Wind-Up Wonder! Run the packing line, wind the racers on the test track, re-teach the sorting scanner and fix the blueprints to unmask the Toy Trickster.
Multi-digit addition, multiplication, and whole-number division. Every question is tagged to a Common Core standard — official wording:
| 4.NBT.B.4 | Fluently add and subtract multi-digit whole numbers using the standard algorithm. |
|---|---|
| 4.NBT.B.5 | Multiply a whole number of up to four digits by a one-digit whole number, and multiply two two-digit numbers, using strategies based on place value and the properties of operations. Illustrate and explain the calculation by using equations, rectangular arrays, and/or area models. |
| 4.NBT.B.6 | Find whole-number quotients and remainders with up to four-digit dividends and one-digit divisors, using strategies based on place value, the properties of operations, and/or the relationship between multiplication and division. Illustrate and explain the calculation by using equations, rectangular arrays, and/or area models. |
This site is built for shared school computers: it runs in the browser with nothing to install, asks for no student accounts and no real names (agents choose a codename like AGENT NOVA), stores nothing on the machine, and shows no ads. Link it from a newsletter, a bookmark bar, or a resource PDF — students are solving within thirty seconds of clicking.
Yes — the whole Starlight Station case at Grade 4 is free, every time. It draws fresh questions from pools on every attempt, so it can be solved again and again. No card details, no trial clock, no account.
No. Tap Start the Mystery, pick a secret agent codename and badge picture (no real names asked, ever), and the case begins. Nothing is saved on the computer — ideal for shared classroom machines and Chromebooks.
Multi-digit addition, multiplication, and whole-number division — aligned to 4.NBT.B.4 and 4.NBT.B.5 and 4.NBT.B.6. The math is the mechanism of the story: solving it is how the clues unlock.
Starlight Station is the free taster. At Number Cadets, every Grade 4 mystery is waiting — the Villain's Vault, the Vanished Volume, the Carnival Caper, Pirate Cove, and the Blooming Bandit — with badges that save, ranks to climb, and per-standard progress tracking for grown-ups.