Welcome to "Pastry Carry Lab", a Grade 2 Regrouping within 1000 mission at the Challenger stretch problem level, staged in a bakery scenario. The mission opens with a hands-on prompt: "Trade sugar cubes to add 845 and 268. First, build 2 bundles of 10 sugar cubes (a stand-in for the hundreds in 268)." Students work with the numbers 845, 268, 2 and reach a final answer of 2 across 3 guided steps.
Behind the story, this lesson builds regrouping within 1000 understanding aligned to CCSS 2.NBT.B.7. The key strategy is: 845 + 268 = 1113.
A common misconception this page surfaces is: Skipping the hundreds column when subtracting. Every column must be touched, even if the digit looks small or matches. Walk the columns right to left. The adaptive Socratic hints move from a small nudge to a fuller strategy, keeping the reasoning visible for students, parents, and teachers.
Grade 2 · Regrouping within 1000
Mission Progress
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Thinking Summary · 1
Mastered[object Object]
[Discovery] Trade sugar cubes to add 845 and 268. First, build 2 bundles of 10 sugar cubes (a stand-in for the hundreds in 268).
1
Active StepDistribute items equally among groups
Everything you need to know about the Socratic experience.
Trade sugar cubes to add 845 and 268. First, build 2 bundles of 10 sugar cubes (a stand-in for the hundreds in 268). Hint: 268 has 2 hundreds. We sketch them as 2 bundles of 10.
How many column regroups (carries or borrows) did this addition require? If you get stuck, the adaptive hint is: Required regroups: 2.
Challenger missions push beyond CCSS expectations with edge cases that surface deeper misconceptions. Within Grade 2 Regrouping within 1000, expect numbers in the corresponding range.
Skipping the hundreds column when subtracting. Every column must be touched, even if the digit looks small or matches. Walk the columns right to left.
Add/Subtract within 100 (Two-digit fluency is the substrate for three-digit regrouping.) Open /grade-2/addsubwithin100 to start that topic's missions.
C-P-A is the Singapore Math sequence proven to deepen number sense: first manipulate physical objects (Concrete), then draw pictures of them (Pictorial), and only then write equations (Abstract). Inquiry AI structures every mission as exactly these three steps — a manipulative, a picture/grid model, and finally the equation. Skipping straight to symbols is the #1 cause of math anxiety; the platform refuses to do it.
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.
