standard_description: Prove theorems about triangles. Theorems include: measures of interior angles of a triangle sum to 180°; base angles of isosceles triangles are congruent; the segment joining midpoints of two sides of a triangle is parallel to the third side and half the length; the medians of a triangle meet at a point.
problem_activity: Narrative
The purpose of this activity is for students to solve a variety of Add to and Take from Result or Change Unknown story problems. Students solve the story problems any way they choose and write an equation that matches the story and has a box around the answer to the question. During the activity synthesis, students consider the different ways to write equations for a story problem.
MLR8 Discussion Supports.
Synthesis: For each method that is shared, invite students to turn to a partner and restate what they heard using precise mathematical language.
Advances: Listening, Speaking
Engagement: Develop Effort and Persistence.
Chunk this task into more manageable parts. Check in with students to provide feedback and encouragement after each chunk.
Supports accessibility for: Social-Emotional Functioning, Attention
Required Materials
Materials to Gather
10-frames
Connecting cubes or two-color counters
Launch
Groups of 2
Give students access to 10-frames and connecting cubes or two-color counters.
"We are going to solve some more story problems about books other kids like to read."
Activity
Read the problems.
5 minutes: independent work time
5 minutes: partner discussion
Student Facing
Mai has read 3 books about dogs.
Diego gives her 4 more books to read.
How many books about dogs will Mai read all together?
Show your thinking using drawings, numbers, or words.
Equation: ________________________________
Noah has 4 books of poetry.
His sister gives him some more books.
Now he has 10 books of poetry.
How many books did his sister give him?
Show your thinking using drawings, numbers, or words.
Equation: ________________________________
Tyler has 7 books about spiders.
He gives 3 of his books to Kiran.
How many books does Tyler have left?
Show your thinking using drawings, numbers, or words.
Equation: ________________________________
Lin has 5 books about outer space.
Her teacher gives her some more books.
Now she has 10 books about outer space.
How many books did Lin's teacher give her?
Show your thinking using drawings, numbers, or words.
Equation: ________________________________
Student Response
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Activity Synthesis
Invite students to share the equation for each problem.
"Why is the answer in different places in our equations?" (Because in some stories we know the two numbers to add together and then the answer is the total. In other problems we know the starting number and the total and the answer is the other number we added.)


aligns: no