Thinking Summary · 1
MasteredVisual Logic: 0 of 1 parts shaded.
[Discovery] There were 12 satellites. Shade the 6 that were recalled — the unshaded parts are what remains.
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Active StepWelcome to "Space Dust Sweeper", a 1st Grade Subtraction mission at the Challenger (stretch) level, staged in our space exploration scenario. The mission opens with a hands-on prompt: "There were 12 satellites. Shade the 6 that were recalled — the unshaded parts are what remains." You'll work with the numbers 12, 6 and arrive at a final answer of 6 across 3 guided steps.
Behind the space exploration story, this lesson is really about subtraction aligned to CCSS 1.OA.A.1. Understanding subtraction as taking from, taking apart, and comparing — within 20. The key strategy this mission asks you to internalise: Start at 12, count back 6.
A general pattern to watch for in 1st Grade subtraction — illustrated with example numbers below, which may differ from this lesson's: Forgetting subtraction is the undo of addition. Play fact-family games: give 3+2=5 and ask for the matching subtraction facts. If you get stuck on "Space Dust Sweeper", 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 1 · Subtraction
Mission Progress
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Thinking Summary · 1
MasteredVisual Logic: 0 of 1 parts shaded.
[Discovery] There were 12 satellites. Shade the 6 that were recalled — the unshaded parts are what remains.
1
Active StepEverything you need to know about the Socratic experience.
There were 12 satellites. Shade the 6 that were recalled — the unshaded parts are what remains. Hint: Tap + until the bar has 12 parts, then tap 6 of them to mark them as recalled.
You know 6 + 6 = 12. So what is 12 − 6? If you get stuck, the adaptive hint is: One fact-family, three equations.
Challenger missions push beyond CCSS expectations with edge cases that surface deeper misconceptions. Within 1st Grade Subtraction, expect numbers in the corresponding range.
Subtracting more than you have (e.g., 3 − 5). With physical objects, show it is impossible at Grade 1. Save negatives for later.
Comparing (Subtraction answers "how many more".). Open /grade-1/comparing to start that topic's missions.
Socratic teaching answers a question with a better question. Instead of "the answer is 12", the system asks "if you had 3 groups of 4, how could you skip-count?" The goal is to externalize the learner's reasoning so they hear themselves think. Every Inquiry AI hint follows this pattern: nudge → reframe → analogy → only then a worked example, in that order.
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.