standard_description: Add within 100, including adding a two-digit number and a one-digit number, and adding a two-digit number and a multiple of 10, using concrete models or drawings and strategies based on place value, properties of operations, and/or the relationship between addition and subtraction; relate the strategy to a written method and explain the reasoning used. Understand that in adding two-digit numbers, one adds tens and tens, ones and ones; and sometimes it is necessary to compose a ten.
problem_activity: Narrative
The purpose of this activity is for students to use a method of their choice, likely multiplication or division, to solve a contextual problem about equal sharing of the longest noodle ever made. The numbers in this activity are larger than the numbers students have worked with in previous lessons on division. Students estimate the number of feet of noodle each person ate at the record breaking event. The numbers and context were chosen to encourage students to consider what they know about the meaning of division, to make a reasonable estimate, and to reason about the meaning of the quotient in the context of the situation presented (MP2).
Monitor and select students with the following strategies to share in the synthesis:
Students use multiplication or division to estimate that each person will get about 25 feet of noodle.
Students can explain why 25 feet of noodle for each person is a low estimate.
Launch
“What kind of noodles do you like to eat?” (ramen, spaghetti, fettucini, chicken noodle soup)
30 seconds: partner discussion
“About how long is one of the noodles you like to eat?” (about 1 foot long)
Groups of 2
Activity
5 minutes: independent work time
5 minutes: partner discussion
As students work, consider asking “What do the numbers in your calculations mean, in terms of the situation?”
Student Facing
A Chinese food company cooked a single noodle measuring about 10,119 ft. It served 400 people.
If the noodle was shared equally, estimate how many feet of noodle each person was served.
Is your estimate lower or higher than the actual length of noodle each person ate? Explain your reasoning without calculating the actual length.
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
Ask selected students to share in the given order (or use the provided student solutions if needed).
“How are the methods for estimating the amount of noodle each person gets the same?”(They both start by giving each person 10 feet of noodle. Then they give more until they have both given 25 feet to each person. They both find multiples of 400.)
“How are they different?” (One thinks of the process as division and one uses just multiplication.)
“How do you know the estimate of 25 feet is too low?” (Because there was still some of the noodle left. There are 119 feet left over.)


aligns: no