CCSS.Math.Content.K.MD.B.3
The standard
Classify objects into given categories; count the numbers of objects in each category and sort the categories by count.
Common Core State Standards for Mathematics · Measurement and Data
What this standard means
Students need to sort objects into teacher-given groups, count how many are in each group, and compare the groups by number. They should use clear sorting rules, such as color, shape, size, or type, and keep one-to-one count as they work.
Mastery looks like a child placing each object in the right group, counting each group accurately, and saying which group has more, fewer, or the same. Common trouble spots are changing the sorting rule halfway through, double-counting objects, skipping objects, and comparing by how spread out a group looks instead of by the count.
Ways to teach it
- Give pairs a cup of buttons and sorting mats labeled red, blue, and yellow, then have them count each group aloud.
- Ask, “How did you know where each object belonged, and which group has the most?” after a class sort.
- Show a mixed set of 10 pattern blocks and ask students to sort by shape, count each group, and circle the largest group.
- Sort classroom snacks by type, such as crackers, raisins, and pretzels, then count which snack choice appears most often.
Plan a lesson for CCSS.Math.Content.K.MD.B.3
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