standard_description: Express a fraction with denominator 10 as an equivalent fraction with denominator 100, and use this technique to add two fractions with respective denominators 10 and 100. (Students who can generate equivalent fractions can develop strategies for adding fractions with unlike denominators in general. But addition and subtraction with unlike denominators in general is not a requirement at this grade.) For example, express 3/10 as 30/100, and add 3/10 + 4/100 = 34/100.
Grade 4 expectations in this domain are limited to fractions with denominators 2, 3, 4, 5, 6, 8, 10, 12, and 100.
problem_activity: Narrative
The purpose of this True or False is for students to demonstrate strategies they have for using equivalent fractions to add and subtract fractions with different denominators. These mental calculations prepare students for working with more complex common denominators during this lesson.
Launch
Display one statement.
“Give me a signal when you know whether the statement is true and can explain how you know.”
1 minute: quiet think time
Activity
Share and record answers and strategy.
Repeat with each statement.
Student Facing
Decide if each statement is true or false. Be prepared to explain your reasoning.
\(\frac{1}{4}+\frac{2}{4}=\frac{3}{4}\)
\(\frac{1}{2}+\frac{1}{4}=\frac{2}{4}\)
\(\frac{3}{4}-\frac{1}{2}=\frac{2}{4}\)
Student Response
Teachers with a valid work email address can
click here to register or sign in
for free access to Student Response.
Activity Synthesis
“How can we find the correct value of
\(\frac{3}{4}-\frac{1}{2}\)
?” (
\(\frac{1}{2}=\frac{2}{4}\)
so
\(\frac{3}{4}-\frac{2}{4}=\frac{1}{4}\)
.)


aligns: no