Thinking Summary · 1
Mastered[object Object]
[Discovery] Place 14 on the number line between 10 and 20.
1
Active Step[Discovery] Place 14 on the number line between 10 and 20.
Number Line
Place the marker on 14.
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10 ⟵ ⟶ 20
Welcome to "Star Rounder", a Grade 3 Rounding to the Nearest Ten or Hundred mission at the Seedling warm-up level, staged in a space scenario. The mission opens with a hands-on prompt: "Place 14 on the number line between 10 and 20." Students work with the numbers 14, 10, 20 and reach a final answer of 20 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 14 on the number line between 10 and 20.
1
Active StepPlace the marker on 14.
Everything you need to know about the Socratic experience.
Place 14 on the number line between 10 and 20. Hint: 14 sits between 10 and 20. Find its exact tick.
What is the next multiple of 10 ABOVE 14? If you get stuck, the adaptive hint is: 10 + 10 = ?
Seedling missions anchor the visual model with small, friendly numbers — ideal as the first attempt at this topic. 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.