Welcome to "Cookie Cost-of-X Lab", a 6th Grade Expressions mission at the Explorer (core) level, staged in our bakery scenario. The mission opens with a hands-on prompt: "Use algebra tiles to build the expression 7x + 9." You'll reason about the numbers 7, 9, 2 across 3 guided steps.
Behind the bakery story, this lesson is really about expressions aligned to CCSS 6.EE.A.2. Write, read, and evaluate expressions in which letters stand for numbers. The key strategy this mission asks you to internalise: Answer: 23.
A general pattern to watch for in 6th Grade expressions — illustrated with example numbers below, which may differ from this lesson's: Reading "3x" as "3 plus x" instead of "3 times x". A coefficient next to a variable means MULTIPLY. 3x = 3 × x. If you get stuck on "Cookie Cost-of-X Lab", 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 6 · Expressions
Mission Progress
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Thinking Summary · 1
Mastered[object Object]
[Discovery] Use algebra tiles to build the expression 7x + 9.
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Active StepBuild 7x + 9 using x-tiles and 1-tiles.
Everything you need to know about the Socratic experience.
Use algebra tiles to build the expression 7x + 9. Hint: Each x-tile counts as one x. Each 1-tile is a unit. You need 7 x-tiles and 9 1-tiles.
In the expression 7x + 9, what is the constant? If you get stuck, the adaptive hint is: Answer: 9.
Explorer missions hit the core abstraction at typical numeric ranges — this is where conceptual mastery is built. Within 6th Grade Expressions, expect numbers in the corresponding range.
Translating "3 less than n" as "3 - n" instead of "n - 3". "Less than" REVERSES the order. "3 less than 10" = 10 - 3 = 7.
Variables (Variables are the substance of expressions.). Open /grade-6/variables 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.
