CK-12 Foundation
Ck 12: Elem Math: Fact Families Numbers to 1000
[Free Registration/Login may be required to access all resource tools.] The video shows how to determine the missing number sentence when adding and subtracting 3-digit numbers by using fact families.
Illustrative Mathematics
Illustrative Mathematics: Cave Game Subtraction
The purpose of this task is for students to practice creating and memorizing subtraction equations while focusing on missing addends. After modeling the activity with the whole class, this game would be perfect for centers and small groups.
CK-12 Foundation
Ck 12: Elem Math: Add and Subtract to 100 Mixed Operations and Word Problems
[Free Registration/Login may be required to access all resource tools.] This is a set of practice problems where students solve addition and subtraction problems in order to determine missing numbers to keep the equation balanced. When...
Room Recess
Roomrecess: Alien Addends
Roomrecess: Alien Addends is an online game where the player's spaceship has to catch the missing numbers to the addition problems.
SMART Technologies
Smart: Colorful Painter Fact Families
Find the missing numbers in the fact family number sentences.
ICT Games
Ict Games: Funky Mummy
Funky Mummy is a mobile-friendly number facts game. Play this game to practice quick recall of addition, subtraction and multiplication facts.
National Council of Teachers of Mathematics
Nctm: Figure This: Which Is Worth More, a Smile or a Frown?
Solve for the value of the smiles and frowns to find out how much a smile is worth, in this activity. A challenge that focuses on number sense, number combinations, and unknowns. Included are examples of how this skill is applied in real...
Illustrative Mathematics
Illustrative Mathematics: Boys and Girls, Variation 2
Students are asked to solve a word problem with both addends unknown. They will write an equation and draw a picture to use to explain their answer.
Math Aids
Math Aids: Number Bonds Worksheets
Great resource to practice and strengthen math skills pertaining to number bonds. Math worksheets are printable, may be customized, and include answer keys.
Lawrence Hall of Science
The Math Page: Skill in Arithmetic: The Meaning of Subtraction, and Mental Calculation
This website explains and defines basic subtraction. There are practice problems at the very end of this lesson.
Math Slice
Math Slice: Heavy Slice Special Test
A concise test for assessing number sense using weights and scales. Assessment is scored online offering students immediate feedback. Can be used for a quick assessment.