In the classroom, the game could work well as an introduction to subtraction. You can start by providing an email address and creating a free classroom account, which will allow you to track individual student progress for up to 30 students. Have kids work individually or take turns in pairs to complete a level, and then reinforce what they learned through a class discussion. As a follow-up, kids can write their own subtraction problems and have their partners draw models to show how to solve the problems.Continue reading Show less
In Teachley: Subtractimals, kids complete subtraction problems, earning blocks along the way. They begin with the tool round: They're given a subtraction sentence to complete and can choose an appropriate strategy to find the answer. There are three strategy choices: count on (where kids count blocks), count back (where kids count backward), and memory (where kids rely on memorized math facts). After kids answer correctly, another subtraction sentence appears and the process repeats several more times. If kids choose the memorization tool and get the answer correct, they earn a golden block. If they choose another strategy and get the answer correct, they earn a green block. And if kids get the incorrect answer, they get a red block.
After the tool round, kids move to the speed round. They have to quickly complete subtraction sentences, one at a time. Kids get two chances, along with hints that relate subtraction to addition, to quickly finish each subtraction sentence before a golden block drops into a boiling pot and disappears forever. For each correct answer completed on the first try, kids earn a golden block. They earn green blocks for second-try answers and red blocks for incorrect answers. Teachers can create classroom accounts to track which subtraction facts kids have memorized and which facts still need work.Continue reading Show less
Teachley: Subtractimals teaches kids how to subtract using a variety of strategies while addressing a handful of Common Core math standards. Kids can learn how to subtract using a conceptual approach that incorporates three strategies: count on, count back, and memory, in which kids subtract mentally. They choose the correct answer using a number line, which further promotes a conceptual understanding of the concept. Kids can use hints in the speed round if needed, and earning blocks to reveal a mysterious illustration is a fun way to keep them engaged. The speed round, where kids race to beat the clock, is particularly engaging. The interactive number line is useful for visualization, but it's sometimes difficult to tap the correct answer, so kids may get it wrong even if they know the correct answer. Still, overall, this is an exciting and comprehensive tool for teaching kids early subtraction strategies.Continue reading Show less
Key Standards Supported
Number And Operations In Base Ten
Understand that the two digits of a two-digit number represent amounts of tens and ones. Understand the following as special cases:
Operations And Algebraic Thinking
Represent addition and subtraction with objects, fingers, mental images, drawings2, sounds (e.g., claps), acting out situations, verbal explanations, expressions, or equations.
Solve addition and subtraction word problems, and add and subtract within 10, e.g., by using objects or drawings to represent the problem.
Fluently add and subtract within 5.
Use addition and subtraction within 20 to solve word problems involving situations of adding to, taking from, putting together, taking apart, and comparing, with unknowns in all positions, e.g., by using objects, drawings, and equations with a symbol for the unknown number to represent the problem.2
Apply properties of operations as strategies to add and subtract.3 Examples: If 8 + 3 = 11 is known, then 3 + 8 = 11 is also known. (Commutative property of addition.) To add 2 + 6 + 4, the second two numbers can be added to make a ten, so 2 + 6 + 4 = 2 + 10 = 12. (Associative property of addition.)
Understand subtraction as an unknown-addend problem. For example, subtract 10 – 8 by finding the number that makes 10 when added to 8.
Relate counting to addition and subtraction (e.g., by counting on 2 to add 2).
Add and subtract within 20, demonstrating fluency for addition and subtraction within 10. Use strategies such as counting on; making ten (e.g., 8 + 6 = 8 + 2 + 4 = 10 + 4 = 14); decomposing a number leading to a ten (e.g., 13 – 4 = 13 – 3 – 1 = 10 – 1 = 9); using the relationship between addition and subtraction (e.g., knowing that 8 + 4 = 12, one knows 12 – 8 = 4); and creating equivalent but easier or known sums (e.g., adding 6 + 7 by creating the known equivalent 6 + 6 + 1 = 12 + 1 = 13).
Fluently add and subtract within 20 using mental strategies.2 By end of Grade 2, know from memory all sums of two one-digit numbers.