0–9 months – See this age across all domains Infants

What educators might observe

• Distinguishes between objects they suck and those they do not
• Smiles when they see or hear familiar caregiver
• Gazes at unfamiliar object or person for longer period of time
• Shows preferences for particular activities, such as being carried rather than pushed in the stroller
• Explores how various toys feel and touches different objects in different ways

Ways educators might support the child's development

• Narrate when familiar individuals enter the room (“Here comes Ms. Kimball. You know Ms. Kimball. Hello, Ms. Kimball.”)
• Notice when a child is wondering about a new object (“You are looking at our new mobile. We hung it up in the window.”)
• Use descriptive vocabulary, such as rough, smooth, furry, bumpy, long, short, wet, and dry as children touch and explore their environment

8–16 months – See this age across all domains Infants

What educators might observe

• Shows preference for particular items such as toys, cups, or clothing
• Knows trash can is something you place items in, but may put objects other than trash in it
• Selects a duck when educator asks, “Where’s the duck?”
• When unfamiliar adult enters the room, may cry or move toward familiar person
• Begins to understand the similarities and differences in speech sounds and distinguishes and imitates patterns of speech
• Chooses to play with the red car even though there is a blue one just like it
• Knows some objects that go together (e.g., puts the doll in a toy stroller)

Ways educators might support the child's development

• Describe objects by their size, color, and shape (“You are rolling the big, red ball.”)
• Talk about which objects go together during caregiving routines (“I am getting ready to change your diaper. I need a clean diaper, wipes, and gloves.”)
• Play language games that emphasize speech sounds; for example, repeat the consonant sounds that the baby makes

15–24 months – See this age across all domains Toddlers

What educators might observe

• Helps clean up environment by putting materials in their places; puts books in basket, for example, or blanket in cubby
• Arranges objects in lines (e.g., makes a row of blocks)
• Points to a duck in a book when the educator asks, “Which one says, ‘quack?’”
• Identifies two identical toys by putting them together (or in response to the question, “Can you find one like this?”)
• Calls all the four-legged animals on a farm “cows,” although some are sheep and some are horses
• Connects objects and ideas, such as using a broom for sweeping or a shovel or cup to scoop sand or water

Ways educators might support the child's development

• Provide intentional collections of toys
  • An animal family with a male, a female, and a young animal
  • A variety of trucks, trains, and cars
  • A doll with a bottle, a brush, and clothes
  • A toy broom, mop, and dustpan
  • A collection of objects that are all the same color
  • A collection of heavy objects
  • A collection of pieces of fabric such as velvet and burlap
• Store and display collections of items in separate, accessible, attractively presented bins

24–36 months – See this age across all domains Toddlers

What educators might observe

• Collects a single type of object (e.g., picks up pinecones on a walk in the park)
• Calls a big animal “Papi” (“Daddy”) and a small animal “Bebe” (“Baby”)
• Begins to sort similar items into categories such as color or shape (e.g., retrieves blue ball when asked, “Could you please get the blue one?”)
• Identifies small, medium, and big objects when arranged in a series
• Uses one-to-one correspondence with objects(e.g., puts one straw in each cup.) objects (e.g., puts one straw in each cup)

Ways educators might support the child's development

• Provide puzzles and toys that encourage matching, such as shape sorters
• Incorporate categorization into games with children; for example, make up a story together in the block area about a family of goats and a family of sheep
• Label the same objects in a group in different ways (“mommy, child, baby” and then “big, small, tiny.”)
• Encourage child to group toys and compare similarities and differences between them (e.g., “Let’s find all the toys with wheels.”)

3-year-olds – See this age across all domains Preschool

What educators might observe

• Shows understanding of the words “same” and “different”
• Remarks on physical differences that they notice among members of the community
• Recognizes and labels aspects of an experience (tall, long, fun)
• Identifies categories of objects, for example, knows that dogs, cats, and cows are all animals

Ways educators might support the child's development

• Openly discuss differences children remark on in their community (“Yes, Mr. Brown has no legs. He uses his electric wheelchair to move around.”)
• Extend this learning about differences (“In what other ways do people move around?”)
• Play simple sorting games with children; for example, dress a paper doll for different kinds of weather
• Read books, such as those by Ann Morris, that show types of shoes, hats, bread, or transportation around the world

4-year-olds – See this age across all domains Preschool

What educators might observe

• Sorts by a given attribute, forming categories
• Uses comparative words (e.g., faster, slower, louder)
• Identifies the measurable attributes of objects such as length or weight and describes them using the appropriate vocabulary (e.g., small, big, short, tall, empty, full, heavy, light)
• Lines up objects in order to determine which is longer
• Fills large containers with cups of water and counts how many cups fit in each container

Ways educators might support the child's development

• Make a simple Bingo game with 9 squares of colors, shapes, or animals; the cards from this game can also be used for a simple matching game
• If children are comparing objects, offer them a standard or non-standard tool for measurement
• Play “duck, duck, goose” using different categories, such as “train, train, car”

5-year-olds – See this age across all domains Preschool

What educators might observe

• Sorts by a single attribute and reclassifies according to another attribute (e.g., sorts writing implements by type and then re-sorts them by color)
• Arranges 5–10 objects shortest to longest, biggest to smallest, or heaviest to lightest
• Compares number of objects by counting, even when one of the objects is bigger, up to 10

Ways educators might support the child's development

• Compare characters in a story or subjects in a non-fiction text
• Create class charts and surveys with student information such as siblings, caretakers, or ways of getting to school; use these to compare aspects of the class
• Compare classroom materials, sorting different sizes or shapes of blocks, for example, and discussing how to use them

6-year-olds – See this age across all domains Early elementary

What educators might observe

• Compares several aspects of something (e.g., compares animals, identifying similarities and differences between the ways they move, eat, and defend themselves)
• Notices and compares changes over time (e.g., compares the length of the day at different times of the year, saying, “It used to be dark when I was picked up.”)
• U ses a repeating unit to measure length (e.g., uses a line of small blocks to measure a book)
• Identifies similarities and differences among the lives of people in different families and communities

Ways educators might support the child's development

• Offer objects for comparison and categorization
  • Photos of animals
  • Collections of rocks or leaves
  • Keys
  • Buttons
• Engage children in using categorization for social good; for example, categorize recycling materials
• Provide unit blocks and rulers for measurement
• Create activities to measure distance (e.g., hold a paper airplane contest, then chart the results in a graph)

7-year-olds – See this age across all domains Early elementary

What educators might observe

• Reverses mental actions (e.g., knows that a ball of clay rolled into a long snake contains the same amount of clay as the ball)
• Chooses a strategy for comparison (e.g., uses graphs to compare their observations of the natural world)
• Understands the need for a standard unit when measuring length

Ways educators might support the child's development

• Offer formats distinctly for comparison and categorization, such as Venn diagrams and three-column charts
• Offer vocabulary such as “traits,” “similar,” and “category”
• Use “greater than” and “less than” to compare quantity
• Compare standard and non-standard units of measure, some of which can be parts of the body; use inches, feet and meters, but also fingers, hands, and items like paper clips

8-year-olds – See this age across all domains Early elementary

What educators might observe

• Creates hierarchical categorizations (e.g., child categorizes plants based on the ecosystems in which they live, then divides the plants that live in the desert into cacti and succulents)
• Compares their home life to that of children who live in different places and to the lives of children who lived a long time ago

Ways educators might support the child's development

• Invite families to visit the classroom to talk about their childhoods; use Venn diagrams to compare and contrast
• Read books aloud about children who live in different kinds of families; ask the children questions about how the character’s lives are similar to and different from their own
• Visit a natural history museum or botanical garden and talk about the categories the curators use