Lesson 20

The purpose of an Estimation Exploration is to practice the skill of estimating a reasonable answer based on experience and known information. 

• Groups of 2
• Display the image.
• “What is an estimate that’s too high? Too low? About right?”
• 1 minute: quiet think time

• “Discuss your thinking with your partner.”
• 1 minute: partner discussion
• Record responses.

• “There are 10 dots. Why was it hard to tell there were 10 dots?” (Usually we see 10 on a 10-frame or fingers or with beads. It was hard to see how many there were because they were scattered.)

The purpose of this activity is for students to use what they know about 10 and what it looks like to estimate whether a group has more or less than 10 images. Students then count the images to see if they estimated correctly. It is important for students to know that there is not always a right answer, particularly when the number of images is close to 10, as in the second and fourth questions. It is important that answers of both “more” and “fewer” are accepted and the emphasis is on students sharing their reasoning (MP3).

• Groups of 2
• “Now we are going to look at some pictures of pencils and think about whether there are more than 10 or fewer than 10 pencils without counting them. Write ‘more’ on the line if you think there are more than 10 pencils. Write ‘fewer’ on the line if you think there are fewer than 10 pencils.”

• 3 minutes: independent work time
• Monitor for a student who writes “more” and a student who writes “fewer” for the second problem.
• “Figure out how many pencils are in each picture and write a number on the line. Were your guesses correct?”
• 3 minutes: partner work time

• Display the image:

  

  

• “Some students said they thought there were more than 10 pencils and some thought there were fewer than 10 pencils. Both of those are good answers.”
• Invite a student to share why they thought there were more than 10.
• Invite a student to share why they thought there were fewer than 10.
• “When groups are close to 10, it is hard to tell whether there are more or fewer than 10 without counting.”

The purpose of this activity is for students to analyze the reasonableness of estimates. It is important for students to know that there is not always a right answer, particularly when the estimate is close to the number of images, as in the third question. It is important that answers to both questions are accepted and the emphasis is on students sharing their reasoning (MP3).

• Groups of 2
• “Elena looked at some pictures and guessed how many there were without counting. We are going to look at the pictures and think about if Elena’s guess could be right.”

• Read the first problem.
• 2 minutes: partner discussion
• Share responses.
• Repeat the steps with the rest of the problems.

• Display the last image of triangles.
• “Do you think 6 or 14 is a better guess for the number of triangles in this picture? Why?” (14 is a better estimate. I can see a 3 on the top and then there are a lot more, so there are more than 6.)

The purpose of this activity is for students to choose from activities that offer practice with number and shape concepts. Students choose from 5 centers introduced in previous units. Students can choose to work at any stage of the centers.

• Shake and Spill
• Number Race
• Grab and Count
• What's Behind My Back?
• Pattern Blocks

Students will continue to choose from these centers in upcoming lessons. Keep the materials from each center organized to use each day.

• Gather materials from:
  • Shake and Spill
  • Number Race
  • Grab and Count
  • What's Behind My Back?
  • Pattern Blocks

• Groups of 2
• “Today we are going to choose from centers we have already learned.”
• Display the center choices in the student book.
• “Think about what you would like to do first.”
• 30 seconds: quiet think time

• Invite students to work at the center of their choice.
• 10 minutes: center work time
• “Choose what you would like to do next.”
• 10 minutes: center work time

• “Tell your partner about a time when you used a math tool to help you during centers. How did the tool help you?”