Lesson 3.11: Solving Open Number Sentences

3.11 Open Sentences
Homework Review
Mental Math
Find the sum or difference.
16 – 5 = ____
8 + 14 = ____
180 + 50 = ____
210 – 30 = ____
92 + 59 = ____
184 – 126 = ____
Math Message
Write your defense in your Math Notebook.
In this sentence, the letter x stands for the
missing number. It is called a variable. You
could have also written it as:
What number could you write in place of the
to change
into a true number sentence?
Open Sentences
A sentence that has a variable in it, like the one
above, is called an open sentence.
To solve the open sentence, replace the variable with
a number that makes the sentence true.
The number that makes the number sentence true is
called the solution.
Let’s try some more…
Rewrite each number sentence on your
whiteboard with the solution in place of the
Circle the solution.
Find the solutions…
Broken Calculator Activity
Solve it using your calculator, but
WITHOUT using the minus key.
More Broken Calculator Problems…
Partner Work – Math Journal page 73.
Independent Work – Math Journal page 74.
Independent Work – Math Journal page 75.
Tonight’s Homework
Math Boxes