Operations and Algebraic Thinking

Add and subtract within 20.

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This Java activity for the interactive white board (free access with registration) provides learners an opportunity to explore number functions and to predict outcomes. Teachers set the desired function from the drop-down list (double it, halve it, add 1, subtract 1, add 10, or subtract 10) and choose the start number from 1-20. Students are asked to predict the outcome before asking the machine to go. There is an option to hide the function so the teacher can ask students to work out what operation is being used to get from the starting number to the number generated. | Activity, Interactive Media Grade Level: K, 1, 2, 3, 4, 5 | |

This activity promotes algebraic thinking of equivalency as well as giving children practice in addition and subtraction. Since there are many different solutions for the values of the unknowns, learners can focus on the idea of working systematically. Students see two weights on one side of an interactive balance, and are asked to find how many different ways they can hang three weights on the other side for it to be balanced. An easier problem, "Number Balance", (cataloged separately) is linked on the problem page. The Teachers' Notes page offers rationale, suggestions for implementation, discussion questions, ideas for extension and support. | Activity, Interactive Media Grade Level: 1, 2, 3 | |

This Nim-like interactive Flash game provides an opportunity to practice basic addition and subtraction while developing strategic thinking through generalization and by applying knowledge of factors and multiples. It can be played against the computer or a friend. Players take turns adding a whole number from 1 to 4 to a running total. The player who hits the target of 23 wins. Computer settings allow changing the target number, the range of numbers to add, who goes first, and whether the player reading the target wins or loses. The Teachers' Notes page offers suggestions for implementation, discussion questions, ideas for support, and links to related games. | Activity, Game, Interactive Media Grade Level: 1, 2, 3, 4, 5 | |

This website, devoted to early numeracy skills, includes links to Happy Numbers teacher accounts, student accounts, and blog. A free teacher account provides access to applets that develop conceptual understanding and procedural fluency. The applets are compatible with interactive whiteboards and tablets. With a subscription teachers can create student accounts and individualize assignments. The blog posts further explain how to utilize these applets in the classroom. | Activity, Interactive Media, Community Grade Level: K, 1, 2 | |

This interactive Flash applet helps students develop number sense and fluency with addition and subtraction facts within 10. Okta hides some bubbles under a shell, and then either adds more bubbles or takes some away. Students determine how many bubbles are left under the shell. Users can choose a specific one-digit starting number or let the applet choose randomly. Users can select addition, subtraction or both. | Activity, Interactive Media Grade Level: K, 1 | |

This webpage offers a variety of games which develop strategic thinking, analytical skills, and basic number skills. Three pdfs provide instructions and materials for sets of games played on reusable boards, on consumable sheets, and with number cards. The only other materials required are counters/chips, dice, and pens/pencils. The site also includes instructions for games that require only counters or paper and pencil. A short article describes the rationale for using such games in the classroom and offers suggestions for organizing and managing games and for maximizing their benefits. | Activity, Game, Instructional Strategy, Instructor Guide/Manual Grade Level: 1, 2, 3, 4, 5 | |

In this problem students practice addition and subtraction (and possibly multiplication) while developing systematic work strategies. Given two types of ladybirds, each with either 4 or 7 spots, learners explore ways of combining them to achieve different total numbers of spots. The Teachers' Notes page offers rationale, suggestions for implementation, discussion questions, ideas for extension and support, and links to related games. | Activity Grade Level: 1, 2, 3 | |

This 5-lesson unit is intended to help children who already understand the meanings of addition to develop fluency with addition facts. The activities and games take advantage of commutativity, the additive identity, doubles, and number patterns to develop operation sense and foster retention. Lessons include student materials, questions for students and teachers, assessment ideas, and links to interactive applets. | Activity, Game, Instructional Strategy, Lesson Plans, Unit of Instruction Grade Level: 1, 2 Resource is part of a PD collection | |

In this 6-lesson unit students use pasta shapes to explore the take away model of subtraction in several different contexts (counting, sets, number line, balanced equations, and inverse of addition). They decompose numbers, explore the zero property, act out subtraction situations with objects and pictures, record differences with vertical and in horizontal notation, create fact families, find differences with a calculator, and compose and solve problems involving subtraction. The lessons include student activity sheets (pdf), questions for student discussion and teacher reflection, assessment options, and links to online applets. | Activity, Game, Lesson Plans, Unit of Instruction Grade Level: K, 1, 2 | |

This problem uses the context of a growing plant in which to practice doubling and also to develop representation and recording strategies. The Teachers' Notes page offers suggestions for implementation and discussion as well as ideas for extension and support. | Activity Grade Level: K, 1, 2, 3 |