Challenger · stretch problem • Addition • 2nd Grade • Bakery scenario

Donut Box Filler: 2nd Grade Addition Practice

Welcome to "Donut Box Filler", a 2nd Grade Addition mission at the Challenger (stretch) level, staged in our bakery scenario. The mission opens with a hands-on prompt: "67 cookies already loaded, and 28 more on the way. Bundle every 10 into one tray. Build 6 trays for the first batch and 2 for the second — each holding 10." You'll work with the numbers 67, 28, 10 and arrive at a final answer of 105 across 3 guided steps.

Behind the bakery story, this lesson is really about addition aligned to CCSS 2.NBT.B.5. Fluently add within 100 using strategies based on place value, properties of operations, and the relationship between addition and subtraction. The key strategy this mission asks you to internalise: Tens: 6 + 2. Ones: 7 + 8. Combine with any trade.

A general pattern to watch for in 2nd Grade addition — illustrated with example numbers below, which may differ from this lesson's: Forgetting to regroup when ones ≥ 10 (e.g., 28 + 37 = 515). Whenever the ones column sums to 10 or more, stop and trade. The ones house can only hold digits 0–9. If you get stuck on "Donut Box Filler", 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 2 · Addition

Donut Box Filler

Mission Progress

0/3

Thinking Summary · 1

Mastered

[object Object]

[Discovery] 67 cookies already loaded, and 28 more on the way. Bundle every 10 into one tray. Build 6 trays for the first batch and 2 for the second — each holding 10.

Active Step

[Discovery] 67 cookies already loaded, and 28 more on the way. Bundle every 10 into one tray. Build 6 trays for the first batch and 2 for the second — each holding 10.

Sharing Lab

Distribute items equally among groups

Tap "+ Add Group" to start distributing.

Groups0 / 8

Items / Group0 / 10

Mastery Expansion

Cookie Batch Baker

Pastry Platter Maker

Macaron Gift Packer

Cookie Batch Baker

FAQ

Common Questions

Everything you need to know about the Socratic experience.

Tap to expand

01 How do I solve the first step of "Donut Box Filler"?

67 cookies already loaded, and 28 more on the way. Bundle every 10 into one tray. Build 6 trays for the first batch and 2 for the second — each holding 10. Hint: Tap "+ Add Group" 8 times. Fill each with exactly 10 items — these are your ten-bundles from 67 and 28.

02 What does the final step of "Donut Box Filler" check?

One more bundle of 10 cookies arrives. What is the new total? If you get stuck, the adaptive hint is: 95 + 10 = ?

03 Why is this mission classified as challenger?

Challenger missions push beyond CCSS expectations with edge cases that surface deeper misconceptions. Within 2nd Grade Addition, expect numbers in the corresponding range.

04 What's a common mistake in 2nd Grade Addition that this mission targets?

Writing the full ten-sum in the ones column (e.g., writing 10 under 4 + 6). Only the ones digit of the sum stays in the ones column. The ten moves up to the tens column as 1.

05 What should I learn after Donut Box Filler?

Subtraction (Same regrouping idea, in reverse — trade a ten back into 10 ones to borrow.). Open /grade-2/subtraction to start that topic's missions.

06 What is the Concrete-Pictorial-Abstract (C-P-A) approach?

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.

07 How is Guided Discovery Learning different from "just letting kids figure it out"?

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.