Explain that tens add to tens and ones add to ones

G1.NBT.19Grade 1Place ValueSource mission: Add Two-Digit Numbers

Articulates the place-value principle underlying two-digit addition and uses it to check a result.

Progress & proof summary

LifecycleNot started

Evidence progress0 of 2 pieces collected

Current predictionNo prediction yet

Next reviewNot scheduled

Mastery projection: Not available yetWhat does this mean?

1.NBT.C.4

can compute correctly but cannot say why, which leaves the method fragile under new formats

These evidence lanes define what would count toward this atom.

EvidencePerformanceStatusNext step

Explain the ideaDescribe why the response works Not startedCollect one observation

Tell it apartDistinguish the target from a near miss Not startedCollect one observation

No evidence recorded yet

The first response record for this atom will appear here.

Recommended next step

Use one focused task to begin collecting evidence for this atom.

Explain the idea

Articulates the place-value principle underlying two-digit addition and uses it to check a result.

Estimated time: ~5 min