Welcome to "Probe Path Jump", a Grade 2 Add/Subtract on a Number Line mission at the Challenger stretch problem level, staged in a space scenario. The mission opens with a hands-on prompt: "Start at 38. Make 5 hops of size 10. Place the END on the number line." Students work with the numbers 38, 5, 10 and reach a final answer of 1 across 3 guided steps.
Behind the story, this lesson builds add/subtract on a number line understanding aligned to CCSS 2.MD.B.6. The key strategy is: 38 + 50 = 88.
A common misconception this page surfaces is: Jumping in the wrong direction for subtraction. Plus = right (toward bigger). Minus = left (toward 0). Picture the arrow before the first hop. The adaptive Socratic hints move from a small nudge to a fuller strategy, keeping the reasoning visible for students, parents, and teachers.
Grade 2 · Add/Subtract on a Number Line
Mission Progress
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Thinking Summary · 1
Mastered[object Object]
[Discovery] Start at 38. Make 5 hops of size 10. Place the END on the number line.
1
Active StepPlace the marker on 88.
Everything you need to know about the Socratic experience.
Start at 38. Make 5 hops of size 10. Place the END on the number line. Hint: Each hop adds +10. From 38, take 5 hops.
Starting from 88, how many MORE hops of size 10 reach 90? If you get stuck, the adaptive hint is: 2 ÷ 10 = 1.
Challenger missions push beyond CCSS expectations with edge cases that surface deeper misconceptions. Within Grade 2 Add/Subtract on a Number Line, expect numbers in the corresponding range.
Jumping in the wrong direction for subtraction. Plus = right (toward bigger). Minus = left (toward 0). Picture the arrow before the first hop.
Add/Subtract within 100 (The number-line view is a second representation of the same arithmetic.) Open /grade-2/addsubwithin100 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.
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.
