T4T Red and Black Cars

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Operations and Algebraic Thinking


Represent and solve problems.

Understand and apply the properties of operations.

Add and subtract within 20.


NC.1.OA.1 Represent and solve addition and subtraction word problems, within 20, with unknowns, by using objects, drawings, and equations with a symbol for the unknown number to represent the problem, when solving:

• Add to/Take from-Change Unknown

• Put together/Take Apart-Addend Unknown

• Compare-Difference Unknown

NC.1.OA.3 Apply the commutative and associative properties as strategies for solving addition problems

NC.1.OA.6 Add and subtract, within 20, using strategies such as:

• Counting on

• Making ten

• Decomposing a number leading to a ten

• Using the relationship between addition and subtraction

• Using a number line

• Creating equivalent but simpler or known sums

Put together-Take Apart/Both Addends Unknown


SF, cubes or counters, two colors (at least 15 of each)


Provide materials to the student. Say: There are 10 cars in the parking lot.  Some of the cars are red and some of the cars are black. How many red cars and how many black cars could be in the parking lot?  Think of as many different ways as you can. Show your strategies with the cubes, drawings, and/or words and write a number sentence for each solution you know.

Provide an example if needed: For example, for the number 3, we know that 2 and 1 equals three.  So, I would write a number sentence that looks like this: 2 + 1 = 3.


Continuum of Understanding


Not Yet Proficient

·         Identifies one or more combinations that do not equal 10

·         Does not write number sentences or writes one or more incorrectly

Strategies Used:

q  Trial and Error

q  Counting All

q  Counting On

q  Basic Facts

q  Doubles

q  Doubles +/- 1,2

Identifies Combinations:

q  0 + 10 &/or 10 + 0

q  1 + 9 &/or 9 + 1

q  2 + 8 &/or 8 + 2

q  3 + 7 &/or 3 + 7

q  4 + 6 &/or 6 + 4

q  5 + 5



·         Shows possible combinations of 10 but does not include all

·         Relies on ‘counting all’ as primary strategy for solving the problem

·         Uses number sentences to record combinations correctly


Meets Expectations

·         Shows all possible combinations of 10 with ease

·         Uses strategies other than counting all

·         Recognizes similar combinations due to the commutative property of addition (e.g., 0 + 10 = 10 + 0)

·         Uses number sentences to record combinations correctly


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