Thinking Summary · 1
Mastered[object Object]
[Discovery] Place 67 on the number line between 60 and 70.
1
Active Step[Discovery] Place 67 on the number line between 60 and 70.
Number Line
Place the marker on 67.
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60 ⟵ ⟶ 70
Welcome to "Star Rounder", a Grade 3 Rounding to the Nearest Ten or Hundred mission at the Explorer core practice level, staged in a space scenario. The mission opens with a hands-on prompt: "Place 67 on the number line between 60 and 70." Students work with the numbers 67, 60, 70 and reach a final answer of 70 across 3 guided steps.
Behind the story, this lesson builds rounding to the nearest ten or hundred understanding aligned to CCSS 3.NBT.A.1. The key strategy is: Halfway rule: if the gap ≥ 5, round UP.
A common misconception this page surfaces is: At the exact halfway (e.g. 35), rounding randomly. Convention: 5 or more rounds up. 35 → 40, not 30. The adaptive Socratic hints move from a small nudge to a fuller strategy, keeping the reasoning visible for students, parents, and teachers.
Grade 3 · Rounding to the Nearest Ten or Hundred
Mission Progress
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Thinking Summary · 1
Mastered[object Object]
[Discovery] Place 67 on the number line between 60 and 70.
1
Active StepPlace the marker on 67.
3rd Grade Rounding to the Nearest Ten or Hundred explorer-2 representative practice page for students who need a crawlable, worked entry point into the topic without exposing every near-duplicate long-tail mission.
This explorer · core practice mission uses a number line to move from the story to a precise rounding to the nearest ten or hundred idea. Work through the prompts in order: notice the structure first, name the quantities, then check whether the final answer fits the original situation.
Common wrong turn: 60 is the lower neighbor. 67 is past it.
Common wrong turn: 67 is closer to 70 (gap = 3) than to 60 (gap = 7).
Common wrong turn: 60 is BELOW 67, not above.
In 3rd Grade Rounding to the Nearest Ten or Hundred, students need to connect the story, the model, and the symbolic answer. The core move here is: Halfway rule: if the gap ≥ 5, round UP. A useful check is to ask whether the answer avoids this pitfall: At the exact halfway (e.g. 35), rounding randomly. Convention: 5 or more rounds up. 35 → 40, not 30.
Everything you need to know about the Socratic experience.
Place 67 on the number line between 60 and 70. Hint: 67 sits between 60 and 70. Find its exact tick.
What is the next multiple of 10 ABOVE 67? If you get stuck, the adaptive hint is: 60 + 10 = ?
Explorer missions hit the core abstraction at typical numeric ranges — this is where conceptual mastery is built. Within Grade 3 Rounding to the Nearest Ten or Hundred, expect numbers in the corresponding range.
At the exact halfway (e.g. 35), rounding randomly. Convention: 5 or more rounds up. 35 → 40, not 30.
Multi-digit Addition (Rounding lets students sanity-check large sums by estimation.) Open /grade-3/addition to start that topic's missions.
Yes. Every mission, handbook page, and topic hub is mapped to a specific CCSS code (visible in the page header). The curriculum follows the CCSS coherence map: Grade 1 number sense → Grade 3 multiplicative thinking → Grade 6 ratio reasoning, with each grade building strictly on the prior year's foundations.
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.