Welcome to "Orbit Path Encoder", a 1st Grade Placevalue mission at the Seedling (entry-level) level, staged in our space exploration scenario. The mission opens with a hands-on prompt: "Build 15 with base-ten blocks. Use 1 ten-rod and 5 units." You'll work with the numbers 15, 1, 5 and arrive at a final answer of 20 across 3 guided steps.
Behind the space exploration story, this lesson is really about placevalue aligned to CCSS 1.NBT.B.2. Understanding that two-digit numbers are built from tens and ones — the power of grouping by 10. The key strategy this mission asks you to internalise: Position gives value: tens digit × 10.
A general pattern to watch for in 1st Grade placevalue — illustrated with example numbers below, which may differ from this lesson's: Writing 24 as "204" (thinking 2 tens + 4 ones = "204"). The tens digit already *counts* tens. You don't add a zero — position does the work. If you get stuck on "Orbit Path Encoder", 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.