Grade 2: 36 skills.

Indented means “needs the one above it first”. A skill with no indent starts from earlier grades.

A hundred as ten tens CCSS-M 2.NBT.1a
- Hundreds, tens & ones CCSS-M 2.NBT.1
  
  Misconceptions recognised: a digit's value is its face value; the unit never changes when you regroup.
  - Comparing three-digit numbers CCSS-M 2.NBT.4
    
    Misconceptions recognised: comparing numbers by the ones digit first.
  - Reading & writing numbers to 1000 CCSS-M 2.NBT.3
    
    Misconceptions recognised: writing numbers as they sound (10023 for 123).
  - Ten or a hundred more & less CCSS-M 2.NBT.8
    
    Misconceptions recognised: adding ten without the carry into hundreds.
  - Three-digit addition CCSS-M 2.NBT.7
    
    Misconceptions recognised: carrying into the wrong column; forgetting the carried ten.
  - Three-digit subtraction CCSS-M 2.NBT.7
    
    Misconceptions recognised: borrowing from a zero without going further left; borrowing without taking one from the next column; taking the small digit from the big one; 0 − n = n; 0 − n = 0.
Add & subtract on the number line CCSS-M 2.MD.6

Misconceptions recognised: reading the ruler's end number without the start.
Bar & picture graphs CCSS-M 2.MD.10
- Line plots CCSS-M 2.MD.9
Counting rows & columns CCSS-M 2.OA.4
- Equal groups — first multiplication Ontario B2
Counting to 1000 CCSS-M 2.NBT.2 · Ontario B1
Crossing 100s when counting up CCSS-M 2.NBT.8

Misconceptions recognised: borrowing upwards when counting past a ten; miscounting across the ten; rolling over one column but not the next; stopping the count at the ten.
- Two-digit subtraction, borrowing CCSS-M 2.NBT.5
  
  Misconceptions recognised: borrowing without taking one from the next column; taking the small digit from the big one.
  - Story problems within 100 CCSS-M 2.OA.1 (part)
    - Two-step story problems CCSS-M 2.OA.1
Even & odd CCSS-M 2.OA.3
Growing patterns Ontario C1

Misconceptions recognised: reading the rule off the last two terms only.
Halves, thirds & fourths CCSS-M 2.G.3
How much longer? CCSS-M 2.MD.4
Measuring from a different start CCSS-M 2.MD.1

Misconceptions recognised: reading the ruler's end number without the start.
Measuring with rulers & units CCSS-M 2.MD.1
- Estimating lengths CCSS-M 2.MD.3
- Same length, different units CCSS-M 2.MD.2
Money to $1 CCSS-M 2.MD.8 · Ontario F1
Moving on a grid Ontario E1

Misconceptions recognised: swapping across and up.
Shapes by sides & corners CCSS-M 2.G.1
Sorting by two attributes Ontario D1.1
Telling time to 5 minutes CCSS-M 2.MD.7

Misconceptions recognised: minute hand read a number too far; swapping the hour and minute hands; reading the hour as the number the hand is nearest; reading the minute hand's number as the minutes.
Two-digit addition CCSS-M 2.NBT.5 (part)
- Adjusting numbers to add easier CCSS-M 2.NBT.5 (strategies) · Ontario B2 (mental math)
  
  Misconceptions recognised: writing the carry into the answer; rounding to add, then forgetting to adjust.
- Two-digit addition with carrying CCSS-M 2.NBT.5
  
  Misconceptions recognised: forgetting the carried ten.
  - Adding several numbers CCSS-M 2.NBT.6
Two-digit subtraction CCSS-M 2.NBT.5 (part)
Which is more likely? Ontario D2

Misconceptions recognised: every outcome is equally likely.

Misconceptions are the rules children reach for that almost work; the names here are the research vocabulary for them. Cardinal Math watches for them as the problem is worked, not just in the answer. The guides under Help for parents walk through the common ones with examples.