Lesson 11

The purpose of this Choral Count is to invite students to practice counting on and counting back from two-digit numbers by 10 and notice patterns in the count. These understandings help students develop fluency with 10 more and 10 less. 

• “Count by 10, starting at 6.”
• Record as students count.
• Stop counting and recording at 116.
• “Count back by 10 starting at 116.”
• Record as students count.
• Stop counting and recording at 6.

• “What patterns do you see?”
• 1-2 minutes: quiet think time
• Record responses.

• “Who can restate the pattern in different words?”
• “Does anyone want to add an observation on why that pattern is happening here?”

In previous lessons, students identified halves and fourths of rectangles and circles and have partitioned these shapes into halves and fourths. The purpose of this activity is for students to reason about the size of halves and fourths of the same shape. Because of their prior work with comparing quantities of objects, students may reason that because four pieces are more than two pieces, a fourth should be larger than a half. When students compare the sizes of a half and fourth of the same-size circle and repeat the comparison with a half and a fourth of the same sized square, they begin to generalize that when you partition the same-size shape into more parts, the size of each part gets smaller (MP8).

• Groups of 2
• Give each student a pair of scissors.

• Read the task statement.
• 10 minutes: partner work time
• Monitor for students who notice that the halves are bigger than the fourths for both shapes.

• Invite previously identified students to share.
• “___ noticed that for both same-sized shapes, a half of the shape was bigger than a fourth of the shape. Do you think that will always be true? Why?” (Yes. When you cut a circle into halves, it is two pieces. Then if you cut it into fourths, you get four smaller pieces. Fourths are smaller than halves of the same-size shape.)

The purpose of this activity is to help students generalize that partitioning the same-size shape into fourths creates smaller pieces than partitioning it into halves. This builds on work from a previous activity in which students compare halves and fourths of circles and squares. Students generalize that for halves and fourths of the same circle, a half is larger than a fourth (and a fourth is smaller than a half). As students explain how they know, some may show or color half of the circle and label it Priya, then show or color a fourth that is not shaded and label it Han. Some students may also shade in part of a half to show fourths. When students decide whether they agree with Priya's or Han's statement and justify their choice with diagrams and words, they construct viable arguments and critique the reasoning of others (MP3).

• Groups of 2
• Give students access to colored pencils or crayons.
• “What are some different types of food that you can share with another person?” (pizza, sandwich, papadum, quesadilla, tortilla)
• “This picture shows roti, a flatbread from India.”

• Read the task statement.
• 5 minutes: partner work time
• Monitor for a student who shows and can explain that a half is bigger than a fourth.

• Invite previously identified students to share.

MLR8 Discussion Supports

• “Who can restate what ____ shared in their own words?”
• Consider providing students time to restate what they heard to a partner before selecting one or two students to share with the class.
• Ask the original speaker if their peer was accurately able to restate their thinking.

The purpose of this activity is for students to learn stage 4 of the Geoblocks center. Students guess which geoblock is inside a bag, without looking at the block.

• Place 4–6 different geoblocks into a bag that is not see-through for each group of 2 students.

• Groups of 2
• Give each group of students a bag containing 4-6 solid shapes. 
• “We are going to learn a new way to play Geoblocks, called Feel and Guess.”
• “One partner will reach into the bag and feel one shape without looking at it. Feel the shape until you can guess which shape it is. Once you guess, remove the shape and show it to your partner. If your partner agrees, put the shape back into the bag, and switch roles.”

• 10 minutes: partner work time

• “What did you feel that helped you guess the shape?” (I felt if the shape had points or not. I felt the shape of the sides on the shape.)