Two Chinese men use the abacus to calculate for their business. "The abacus was one of the earliest aids to calculation." -Hill, 1921

Chinese Abacus

Two Chinese men use the abacus to calculate for their business. "The abacus was one of the earliest…

Illustration of a child holding blocks that can be used to write mathematics story problems involving addition, subtraction, and counting.

Child Counting Blocks

Illustration of a child holding blocks that can be used to write mathematics story problems involving…

Illustration of a child counting books by twos that can be used to write mathematics story problems involving addition, subtraction, and counting.

Child Counting Books

Illustration of a child counting books by twos that can be used to write mathematics story problems…

A machine for adding and subtracting by mechanical means.

Calculating machine

A machine for adding and subtracting by mechanical means.

Illustration of 20 chicks that can be counted by twos. It can be used to write mathematics story problems involving addition, subtraction, and counting.

Counting Chicks by Twos

Illustration of 20 chicks that can be counted by twos. It can be used to write mathematics story problems…

Illustration of children playing darts that can be used to write mathematics story problems involving addition, subtraction, and comparison.

Children Playing Darts

Illustration of children playing darts that can be used to write mathematics story problems involving…

Illustration of a child buying doll clothes. It can be used to write mathematics story problems involving addition, subtraction, money, and counting.

Child Buying Doll Clothes

Illustration of a child buying doll clothes. It can be used to write mathematics story problems involving…

Illustration of a child buying doll toys. It can be used to write mathematics story problems involving addition, subtraction, money, and counting.

Child Buying Doll Toys

Illustration of a child buying doll toys. It can be used to write mathematics story problems involving…

Illustration of woman selling food in dozens that can be used to write mathematics story problems involving addition, subtraction, and counting.

Woman Selling Dozens of Items

Illustration of woman selling food in dozens that can be used to write mathematics story problems involving…

Illustration of a 6 toy elephants and a toy man that can be used to write mathematics story problems involving addition, subtraction, and counting.

6 Toy Elephants

Illustration of a 6 toy elephants and a toy man that can be used to write mathematics story problems…

Illustration of 6 children playing a game that can be used to write mathematics story problems involving addition, subtraction, and counting.

6 Children Playing Game

Illustration of 6 children playing a game that can be used to write mathematics story problems involving…

Illustration of a child buying groceries. It can be used to write mathematics story problems involving addition, subtraction, money, and counting.

Child Buying Groceries

Illustration of a child buying groceries. It can be used to write mathematics story problems involving…

Illustration of a jack-in-the box and 2 dolls. It can be used to write mathematics story problems involving addition, subtraction, and counting.

Jack-in-the box And Dolls

Illustration of a jack-in-the box and 2 dolls. It can be used to write mathematics story problems involving…

Illustration of a child holding a kite that can be used to write mathematics story problems involving addition and subtraction. For example: John's kite tail was 4 feet long. 1 foot of it broke off. How many feet were left?

Child Holding A Kite

Illustration of a child holding a kite that can be used to write mathematics story problems involving…

Illustration of Little Bo Peep and sheep. It can be used to write mathematics story problems involving addition, subtraction, and counting.

Little Bo Peep And Sheep

Illustration of Little Bo Peep and sheep. It can be used to write mathematics story problems involving…

A calculator that performs simple arithmetic functions

Adding Machine

A calculator that performs simple arithmetic functions

A girl doing math problems on the chalkboard.

Math

A girl doing math problems on the chalkboard.

Illustration of children holding number cards that can be used to write mathematics story problems involving addition, subtraction, and comparison.

Children Holding Number Cards

Illustration of children holding number cards that can be used to write mathematics story problems involving…

Illustration of a child with 8 quarts and 1 peck. He is using the baskets to practice measuring. It can be used to write mathematics story problems involving addition, subtraction, money, measurement, and counting.

Child Measuring Using Pecks And Quarts

Illustration of a child with 8 quarts and 1 peck. He is using the baskets to practice measuring. It…

Illustration of three rabbits and a carrot that can be used to write mathematics story problems involving addition and subtraction.

Three Rabbits With Carrot

Illustration of three rabbits and a carrot that can be used to write mathematics story problems involving…

Illustration of two rabbits and 8 carrots that can be used to write mathematics story problems involving addition and subtraction.

Two Rabbits With 8 Carrots

Illustration of two rabbits and 8 carrots that can be used to write mathematics story problems involving…

A teacher helps students do math with a sand table, a predecessor to the abacus.

Sand Table

A teacher helps students do math with a sand table, a predecessor to the abacus.

Illustration of a child playing with toy soldiers. It can be used to write mathematics story problems involving addition, subtraction, and counting.

Child Playing With Toy Soldiers

Illustration of a child playing with toy soldiers. It can be used to write mathematics story problems…

Illustration of a child buying toys. It can be used to write mathematics story problems involving addition, subtraction, money, and counting.

Child Buying Toys

Illustration of a child buying toys. It can be used to write mathematics story problems involving addition,…

Illustration of a child buying toys from another boy. It can be used to write mathematics story problems involving addition, subtraction, money, and counting.

Child Buying Toys

Illustration of a child buying toys from another boy. It can be used to write mathematics story problems…

Illustration of toys that can be counted by twos. It can be used to write mathematics story problems involving addition, subtraction, and counting.

Counting Toys by Twos

Illustration of toys that can be counted by twos. It can be used to write mathematics story problems…

Illustration of a group of toys. It can be used to write mathematics story problems involving addition, subtraction, and counting.

Group of Toys

Illustration of a group of toys. It can be used to write mathematics story problems involving addition,…

Illustration of a group of toys. It can be used to write mathematics story problems involving addition, subtraction, and counting.

Group of Toys

Illustration of a group of toys. It can be used to write mathematics story problems involving addition,…

Illustration of a child playing with train cars. It can be used to write mathematics story problems involving addition, subtraction, and counting.

Child Playing With Train Cars

Illustration of a child playing with train cars. It can be used to write mathematics story problems…

Illustration of 3 dolls in a train. It can be used to write mathematics story problems involving addition, subtraction, and counting.

3 Dolls In Train

Illustration of 3 dolls in a train. It can be used to write mathematics story problems involving addition,…

Illustration of a tree branch with 7 birds and one flying away. It can be used to write mathematics story problems involving addition and subtraction. For example: 8 birds were on the tree. One flew away. How many feet were left?

8 Birds On A Tree Branch

Illustration of a tree branch with 7 birds and one flying away. It can be used to write mathematics…

Illustration of toy trees and building with a toy man that can be used to write mathematics story problems involving addition, subtraction, and counting.

Toy Trees

Illustration of toy trees and building with a toy man that can be used to write mathematics story problems…

Illustration of the resultant vector when two vectors are acting upon a body at point P at 90 degrees.

Resultant Vector With Vectors at 90 degrees

Illustration of the resultant vector when two vectors are acting upon a body at point P at 90 degrees.

Illustration of the resultant vector when two vectors are acting upon a body at point P.

Resultant Vectors

Illustration of the resultant vector when two vectors are acting upon a body at point P.

Illustration of the resultant vector when two vectors are acting upon a body at point P at Ǝ degrees.

Resultant Vector With Vectors at Angle Ǝ

Illustration of the resultant vector when two vectors are acting upon a body at point P at Ǝ degrees.

Illustration of the resultant vector when four vectors are acting upon a body at point P.

Resultant Vector From 4 Forces

Illustration of the resultant vector when four vectors are acting upon a body at point P.