Grade 3: 35 skills.

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

Grams, kilograms & liters CCSS-M 3.MD.2
Kinds of quadrilaterals CCSS-M 3.G.1

Misconceptions recognised: a square can't be a rectangle.
Making change Ontario F1
Multiplication as equal groups CCSS-M 3.OA.1 · Ontario B2

Misconceptions recognised: adding instead of multiplying.
- Division as grouping CCSS-M 3.OA.2
  
  Misconceptions recognised: dividing the small number by the big one.
- Division as sharing CCSS-M 3.OA.2
  
  Misconceptions recognised: dividing the small number by the big one.
- Multiplying by 1 and 0 CCSS-M 3.OA.5/9
  
  Misconceptions recognised: anything times zero is itself.
- Number patterns CCSS-M 3.OA.9
Perimeter CCSS-M 3.MD.8

Misconceptions recognised: mixing up area and perimeter.
Rounding to 10s & 100s CCSS-M 3.NBT.1

Misconceptions recognised: cutting the number off instead of rounding; rounding at the wrong place.
Scaled bar & picture graphs CCSS-M 3.MD.3

Misconceptions recognised: reading each picture symbol as one.
Sorting by three attributes Ontario D1.1
Splitting shapes into rows & columns CCSS-M 2.G.2
- Area by counting squares CCSS-M 3.MD.5-6
  
  Misconceptions recognised: counting the squares on the edge twice.
  - Splitting shapes into equal parts CCSS-M 3.G.2
- Multiplication as arrays & area CCSS-M 3.OA.1 / 3.MD.7
  - Area by multiplying CCSS-M 3.MD.7
    - Area of combined shapes CCSS-M 3.MD.7d
  - Breaking a product into parts CCSS-M 3.OA.5
    
    Misconceptions recognised: splitting a factor and adding the parts back.
  - Order doesn't change a product CCSS-M 3.OA.5 (part)
    
    Misconceptions recognised: adding instead of multiplying.
    - Division as a missing factor CCSS-M 3.OA.6
    - Times tables within 100 CCSS-M 3.OA.7
      
      Misconceptions recognised: adding instead of multiplying.
      - Dividing within 100 CCSS-M 3.OA.7
        
        Multiply & divide stories CCSS-M 3.OA.3
        
        Misconceptions recognised: dividing the small number by the big one; adding instead of multiplying.
        
        Two-step stories, mixed operations CCSS-M 3.OA.8
      - Multiplying by tens CCSS-M 3.NBT.3
        
        Misconceptions recognised: doubling the zeros when multiplying tens; dropping a zero when multiplying tens.
Telling time to the minute CCSS-M 3.MD.1

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.
- Elapsed time CCSS-M 3.MD.1
  
  Misconceptions recognised: elapsed time as if an hour had 100 minutes.
Unit fractions (1⁄2, 1⁄3, 1⁄4) CCSS-M 3.NF.1
- Fractions like 3⁄4 CCSS-M 3.NF.1
  - Equivalent fractions, first steps CCSS-M 3.NF.3ab
    
    Misconceptions recognised: adding the same number to top and bottom.
  - Whole numbers as fractions CCSS-M 3.NF.3c
- Fractions on the number line CCSS-M 3.NF.2
  
  Misconceptions recognised: placing a fraction by its top number alone.
  - Comparing fractions CCSS-M 3.NF.3d
    
    Misconceptions recognised: bigger numbers mean a bigger fraction.
- Line plots with halves & quarters CCSS-M 3.MD.4

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.