Welcome to "Fleet Calculator", a 4th Grade Multidigitmult mission at the Challenger (stretch) level, staged in our space exploration scenario. The mission opens with a hands-on prompt: "Decompose 42 × 18 into place-value parts and fill each cell of the partial-products box." You'll reason about the numbers 42, 18 across 3 guided steps.
Behind the space exploration story, this lesson is really about multidigitmult aligned to CCSS 4.NBT.B.5. Multiply a whole number of up to four digits by a one-digit number, and multiply two two-digit numbers, using strategies based on place value. The key strategy this mission asks you to internalise: 42 × 18 = ?
A general pattern to watch for in 4th Grade multidigitmult — illustrated with example numbers below, which may differ from this lesson's: Multiplying only ones × ones and tens × tens (skipping the cross terms). The area model has *four* boxes for a reason. Every digit on top must meet every digit on the bottom. If you get stuck on "Fleet Calculator", the adaptive Socratic hints below escalate from a gentle nudge to a worked-out strategy — the same way a one-on-one tutor would coach you through it.
Grade 4 · Multidigitmult
Mission Progress
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Thinking Summary · 1
Mastered[object Object]
[Discovery] Decompose 42 × 18 into place-value parts and fill each cell of the partial-products box.
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Active StepDecompose 42 × 18 into place-value parts. Fill each cell, then sum.
| × 40 | × 2 | |
|---|---|---|
| 10 × | ||
| 8 × |
Everything you need to know about the Socratic experience.
Decompose 42 × 18 into place-value parts and fill each cell of the partial-products box. Hint: Break 42 into tens + ones, 18 into tens + ones, then multiply each pair.
Does 18 × 42 give the same answer as 42 × 18? If you get stuck, the adaptive hint is: Same factors, same product, regardless of order.
Challenger missions push beyond CCSS expectations with edge cases that surface deeper misconceptions. Within 4th Grade Multidigitmult, expect numbers in the corresponding range.
Misaligning partial products before summing. Use graph paper or column lines. Partial products live in different place-value columns and must stack accordingly.
Factors (Multiplication facts are the raw material for finding factor pairs.). Open /grade-4/factors to start that topic's missions.
Inquiry-based learning starts with a question, not a formula — students explore, hypothesize, and verify before being told the rule. In Inquiry AI, every mission opens with a "Discovery" step (manipulate the model), then "Abstraction" (write the equation), then "Reflect" (apply to a new case). The procedure is never given upfront; learners derive it from their own observations.
Pure discovery is inefficient — kids hit a wall and quit. Guided Discovery scaffolds the path: a careful sequence of questions, models, and adaptive hints leads the learner toward the insight without revealing it. Inquiry AI's hint system fires automatically after ~15s of hesitation or on the first mistake, escalating from a Socratic nudge to a worked example only when needed. Mistakes are diagnosed via "misconception keys" so the hint matches the actual wrong-thinking pattern.
