📐 Common Core math practice · Grade 4
Fourth grade is where arithmetic gets long. Multiplying four digits by one, dividing with remainders that actually have to be interpreted, adding multi-digit numbers with the standard algorithm — the individual steps are familiar, but there are now enough of them that a single careless slip ruins the answer. That is a hard thing to practise, because the failure is boring and the child knows it. Making it a case helps: when the remainder decides how many pirates get a share, or whether the vault's factor lock is prime, a wrong answer is a plot event rather than a red cross. Fourth grade is also where decimals and fractions stop being separate countries.
🎖️ Start the free Grade 4 mystery See plans
Skill focus: Multiply, divide & multi-digit add
The station's navigation and reactor logs were tampered with and the spare fuel cells are gone. Crunch the numbers to set things right and unmask the saboteur.
🎖️ Play free now → About this caseSkill focus: Factors & primes, multi-digit + ×
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: Decimals, elapsed time & change
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: Number rules, unit conversion, addition & right angles
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: Decompose fractions, multi-digit ×/+
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: Place value ×10, area formula, distance problems & fraction plots
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 4 cases your cadet multiplies up to four digits by one digit and two two-digit numbers, divides four-digit dividends by one-digit divisors with remainders, and adds and subtracts multi-digit numbers using the standard algorithm. They read, write and compare multi-digit numbers, recognize that each place is ten times the one to its right, find all factor pairs to 100 and identify primes and composites, generate and analyze number patterns, and solve multistep word problems interpreting remainders. They compare decimals to hundredths, decompose fractions into sums with a common denominator, convert measurement units, apply area and perimeter formulas, plot fractional measurements, and classify figures by parallel lines, perpendicular lines and right angles.
Every question is tagged to one of these 15 standards, and mastery is tracked per standard for each agent. Official Common Core wording:
| 4.G.A.2 | Classify two-dimensional figures based on the presence or absence of parallel or perpendicular lines, or the presence or absence of angles of a specified size. Recognize right triangles as a category, and identify right triangles. |
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| 4.MD.A.1 | Know relative sizes of measurement units within one system of units including km, m, cm; kg, g; lb, oz.; l, ml; hr, min, sec. Within a single system of measurement, express measurements in a larger unit in terms of a smaller unit. Record measurement equivalents in a two column table. |
| 4.MD.A.2 | Use the four operations to solve word problems involving distances, intervals of time, liquid volumes, masses of objects, and money, including problems involving simple fractions or decimals, and problems that require expressing measurements given in a larger unit in terms of a smaller unit. Represent measurement quantities using diagrams such as number line diagrams that feature a measurement scale. |
| 4.MD.A.3 | Apply the area and perimeter formulas for rectangles in real world and mathematical problems. |
| 4.MD.B.4 | Make a line plot to display a data set of measurements in fractions of a unit (1/2, 1/4, 1/8). Solve problems involving addition and subtraction of fractions by using information presented in line plots. |
| 4.NBT.A.1 | Recognize that in a multi-digit whole number, a digit in one place represents ten times what it represents in the place to its right. |
| 4.NBT.A.2 | Read and write multi-digit whole numbers using base-ten numerals, number names, and expanded form. Compare two multi-digit numbers based on meanings of the digits in each place, using >, =, and < symbols to record the results of comparisons. |
| 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. |
| 4.NF.B.3.b | Decompose a fraction into a sum of fractions with the same denominator in more than one way, recording each decomposition by an equation. Justify decompositions, e.g., by using a visual fraction model. |
| 4.NF.C.7 | Compare two decimals to hundredths by reasoning about their size. Recognize that comparisons are valid only when the two decimals refer to the same whole. Record the results of comparisons with the symbols >, =, or <, and justify the conclusions, e.g., by using a visual model. |
| 4.OA.A.3 | Solve multistep word problems posed with whole numbers and having whole-number answers using the four operations, including problems in which remainders must be interpreted. Represent these problems using equations with a letter standing for the unknown quantity. Assess the reasonableness of answers using mental computation and estimation strategies including rounding. |
| 4.OA.B.4 | Find all factor pairs for a whole number in the range 1—100. Recognize that a whole number is a multiple of each of its factors. Determine whether a given whole number in the range 1—100 is a multiple of a given one-digit number. Determine whether a given whole number in the range 1—100 is prime or composite. |
| 4.OA.C.5 | Generate a number or shape pattern that follows a given rule. Identify apparent features of the pattern that were not explicit in the rule itself. |
Scale and precision. The operations are the same four, but the numbers are multi-digit, the algorithms are formal, remainders have to be interpreted rather than ignored, and decimals appear alongside fractions for the first time.
Very common at this grade — it's usually an arithmetic slip inside a long procedure, not a misunderstanding. Because mastery is tracked per standard, you can see whether the concept is secure and the execution is slipping, which is a different problem needing different practice.
The Family plan covers your household with a personal agent login per child, so progress, badges and mastery are tracked separately for each of them.
Yes. Every question is tagged to a specific Grade 4 standard, listed in full on this page with official wording, and mastery is tracked per standard.