Khan Academy
Khan Academy: Addition & Subtraction: Find the Missing Value
Practice finding the missing value in an addition or subtraction equation involving negative numbers.
CK-12 Foundation
Ck 12: Elem Math: Adding and Subtracting With Parentheses
[Free Registration/Login may be required to access all resource tools.] The resource includes a video tutorial on how to find a missing number in a multi-operational problem by working backwards. The video is followed by practice...
CK-12 Foundation
Ck 12: Elem Math: Calculating Sums (Numbers Up to 100,000)
[Free Registration/Login may be required to access all resource tools.] In this learning module, students are presented with a set of numbers up to 100,000, most of which end with one or more zeroes, and must apply their understanding of...
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 describes how to determine what number sentence is missing in the fact family.
CK-12 Foundation
Ck 12: Elem Math: Fact Families Numbers to 100
[Free Registration/Login may be required to access all resource tools.] The video shows how to determine the missing number sentence by using fact families.
CK-12 Foundation
Ck 12: Elem Math: Completing the Addition Sentence Sums to 20
[Free Registration/Login may be required to access all resource tools.] The video shows how to count backwards to determine the missing number in an addition problem. The video is followed by practice problems to assess student...
Scholastic
Scholastic: Math Maven's Mysteries: The Cuckoo Caper
The famous Clockenheimer Cuckoo is missing from Clockenheimer Clocks on Main Street! Help Math Maven get it back by solving a math riddle.
Scholastic
Scholastic: Math Maven's Mysteries: The Case of the Hatcher Hotel Heist
Help Math Maven solve this mystery! Items are missing from several hotel rooms, but some addition and subtraction clues have been left behind. Use your skills to figure out where the thief will strike next!
CK-12 Foundation
Ck 12: Elem Math: Add, Subtract, and Multiply With Parentheses Missing Number
[Free Registration/Login may be required to access all resource tools.] This is a video and practice problems demonstrate finding missing numbers using order of operations and working backwards. Operations include addition, subtraction,...
CK-12 Foundation
Ck 12: Elem Math: Filling in the Missing or Sign Numbers to 100
[Free Registration/Login may be required to access all resource tools.] The video works through 2-digit addition and subtraction problems to determine which number sentence coincides with the given value. The video is followed by...
CK-12 Foundation
Ck 12: Elem Math: Filling in the Missing or Sign Numbers to 1000
[Free Registration/Login may be required to access all resource tools.] The video works through a 3-digit addition problem to determine if the correct operation for the number sentence is addition or subtraction. The video is followed by...
Math Slice
Math Slice: Math Crossword Slice Special Test
Use this interactive math crossword puzzle to build number sense skills. Simply fill in the missing numbers based on the operation. Immediate feedback given to responses.
CK-12 Foundation
Ck 12: Elem Math: Balancing the Equations Numbers to 1000
[Free Registration/Login may be required to access all resource tools.] The video shows how to use addition and subtraction to keep an equation balanced by working backwards to determine the missing value. The video is followed by...
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.
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.
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.
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...
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.
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 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.