B1. Number Sense
Demonstrate an understanding of numbers and make connections to the way numbers are used in everyday life.
Learning Situation 1: The Magic of Numbers (Counting)
Duration: approximately 2 hours
Overall Expectation | Specific Expectations |
B1. Number Sense Demonstrate an understanding of numbers and make connections to the way numbers are used in everyday life. |
B1.1 Read, represent, compose, and decompose whole numbers up to and including 200, using a
variety of tools and strategies, and describe various ways they are used in everyday life.
B1.3 Estimate the number of objects in collections of up to 200 and verify their estimates by counting. B1.4 Count to 200, including by 20s, 25s, and 50s, using a variety of tools and strategies. |
Learning Goals
The purpose of this learning situation is to allow the student to:
- recognize regularities in numbers;
- add mentally.
Learning Context | Prerequisites |
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In Grade 2 , students further explore number patterns by counting by 1 and in intervals of 2, 5, 10, 25, and 50, up to 200. The use of grids, number charts, and the calculator allow students to explore counting patterns in a tactile and visual way to perform operations involving two-digit numbers. | In this learning situation, students will:
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Materials
Main Activity
- Appendix 2D.1 (Blank Hundreds Chart)
- Appendix 2D.2 (Hundreds Chart)
- manipulatives (for example, counters)
- magic wand or wizard hat (optional)
- calculator
Additional Activity 1
- Appendix 2D.2 (Hundreds Chart) (one copy per team)
- calculators (one per pair)
- counters
- calculator
Additional Activity 2
- Appendix 2D.1 (Blank Hundreds Chart) (one copy per student)
- Appendix 2D.2 (Hundreds Chart) (if required)
- counters
Additional activity 3
- Appendix 2D.2 (Hundreds Chart) (several copies)
- reusable plastic bags
Mathematical Vocabulary
pattern, hundreds chart, hundreds carpet, calculator
Before Learning (Warm-Up)
Duration: approximately 30 minutes
Use a blank hundreds carpet or place an enlarged copy of Appendix 2D.1 on the floor, or alternatively, project Appendix 2D.1 on the wall or interactive whiteboard.
Ask students to sit in front of the grid so that everyone has the same perspective.
Begin the Landing Position game by throwing a small object (for example, a two-colour counter) onto the grid or carpet. Ask students to guess the number in the box where the object landed and explain their method for determining that number.
Ask students to communicate their thinking and justify their reasoning. For example, if the token falls on 32, a student might say, 'I counted to 2, then I counted down in increments of 10—so 2, 12, 22, down to 32.'
Vary the activity by saying a number and then asking a student to place an object on the corresponding square of the grid or move to that location on the mat.
Active Learning (Exploration)
Duration: approximately 45 minutes
Use a blank hundreds carpet or place an enlarged grid (Appendix 2D.1) on the floor and have students participate in the Number Magic game.
Clarify the various roles that students are to play.
- The number wizard: The role of the number wizard is to choose a number and designate another student to become the apprentice in search of the number. The student may wear a special hat or use a magic wand.
- The apprentice: The role of the apprentice is to discover the chosen number and to describe orally their movements on the grid to arrive at this number.
- The verifier: The verifier's role is to record and verify, with the help of a calculator, the apprentice's movements on the mat or grid.
Designate three students to act out the roles.
Ask the number wizard to choose a number less than 50, and then ask the apprentice to go to the corresponding box.
Invite the number wizard to choose another number to add to the first.
Invite the apprentice to determine the sum of the two numbers and to move to the square corresponding to the total. The student moves one square at a time and describes to the class their moves.
Example
The number wizard chooses 23. The apprentice goes to the corresponding square. The magician decides that the number 34 must be added to 23. The apprentice can move down to square 33, which is a jump of 10, then to square 43, which is another 10, and to square 53 for a final jump of 10. The apprentice then moves one square at a time from 53 to 57, which is the destination. The verifier uses a felt-tip pen to trace the moves on a grid as the apprentice describes them.
Note: This grid will be used during the consolidation stage to analyze the movements of the apprentices and to make a formative assessment of each student. If the same grid is used to record the movements of each team member, use different coloured markers.
Repeat the game until each team member has played all three roles.
Group students into teams of three. Provide each team with a copy of Appendix 2D.1 and counters.
Observe students playing and note their strategies used to determine numbers and add them up.
Record your observations in an anecdotal record or use a checklist to record strategies used by the student.
Consolidation of Learning
Duration: approximately 40 minutes
Share and discuss the various strategies used during the game.
Analyze, with the students, the moves recorded on the grid or the strategies used during the game.
Ask students the following questions:
- What is the fastest way to determine the starting point?
- What patterns did you notice?
- What made the game easier?
- How do you think this game would help someone add up two-digit numbers?
- How would the game be different if the magician had asked you to subtract a number from the starting number?
- Why did you decide to...?
- How would you get to the square...?
- How could we get to the square any faster?
- Would there be a different way to get to the square...?
Examples of Success Criteria
The student:
- uses an effective strategy for adding numbers;
- uses patterns to determine numbers on the grid or number carpet;
- properly explains their movements.
Differentiated Instruction
The activity can be modified to meet the needs of the students.
To Facilitate the Task | To Enrich the Task |
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Follow-Up at Home
Extension 1: Secret Formulas
Group students into teams of two. Give each team a hundreds chart (Appendix 2D.2).
Enter an operation in a calculator that involves repeating a number (for example, 5 + 5). Press the [=] key to show the first number in the pattern.
Ask each team to place a counter on the square of the chart corresponding to the number.
Continue to press the [=] key as students add counters to the chart to represent the new numbers that appear on the calculator until a student discovers the pattern and names it.
Repeat the game two or three times.
Distribute a calculator to each team or use the calculator on the computers. Have students play the game: one student uses the calculator and the other uses the hundreds chart. The roles are reversed each time the solution to a game is found.
Modify the task by asking students to use two different numbers in the operation (for example, 2 + 5), which makes it more difficult to discover a pattern, or to subtract rather than add.
Extension 2: Missing Numbers
Group students into pairs. Give each student a copy of Appendix 2D.1.
Have one student from each team secretly cover four or five spaces on the chart with counters.
Invite each partner to guess the numbers and explain how they were able to figure them out (for example, "It was the 4th number in the 3rd row, so I knew it was 34.")
Point out to students the strategies used to discover the missing numbers on the hundreds chart.
Facilitate the task of struggling students by using the hundreds chart (Appendix 2D.2).
Extension 3: Puzzles (reconstructing a hundreds chart)
Make several copies of Appendix 2D.2.
Cut out the hundreds chart in a variety of ways (for example, in strips, columns, or groups of 2, 4, or 5 squares…) and place the pieces of each chart in a plastic bag.
Distribute the bags to students and invite them to reconstruct the charts, an activity that serves to reinforce various concepts in numeration and number sense.
Source: translated from Guide d'enseignement efficace des mathématiques de la 1re à la 3e année, Numération et sens du nombre, p. 131-136.
Learning Situation 2: What is Your Estimation?
Duration: approximately 2 hours
Overall Expectation | Specific Expectations |
B1. Number Sense Demonstrate an understanding of numbers and make connections to their use in daily life. |
B1.1 Read, represent, compose, and decompose whole numbers from 0 to 200, using a variety of tools and strategies, in a variety of contexts, and describe how they are used in everyday life. B1.3 Estimate the number of objects in collections of up to 200 and verify their estimates by counting. |
Learning Goals
The purpose of this learning situation is to allow the student to:
- establish relationships between quantities of objects and numbers;
- to make increasingly accurate estimations;
- to establish benchmarks to facilitate estimations;
- to explain their estimation strategies.
Learning Context | Prerequisites |
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The student's ability to estimate is closely related to their understanding of quantity.
This skill helps the student use logic and reasoning in problem solving situations. The student who has difficulty estimating cannot evaluate the reasonableness of an answer. The student who automatically assumes that a large container holds 200 objects, regardless of whether the objects are small or large, has not fully understood estimation. The use of benchmarks as an estimation strategy enables students to improve the accuracy of their estimations. A benchmark is a known and understood quantity. Knowing the quantity represented by a benchmark makes it possible to explore or estimate the number of objects included in a larger or smaller set. For example, students can more easily estimate the quantity of a large number of blocks by first counting out 10 blocks. The benchmark of 10 blocks allows them to consider the number of how many groups of 10 are in the set, and then using that information to estimate the total number of blocks in the set. |
In this learning situation, students will:
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Materials
- appendix 2Q.1 (Sample Estimation Chart)
- appendix 2Q.2 (What is Your Estimate?) (one copy per student)
- clear containers or reusable plastic bags (one per pair)
- objects to fill containers or bags (for example, table tennis balls, marbles, golf balls, popcorn, dried beans)
- sticky notes
Mathematical Vocabulary
estimation, near, double, half, benchmark
Before Learning (Warm-Up)
Duration: approximately 40 minutes
Place identical objects (for example, table tennis balls, marbles, golf balls, popcorn, dried beans), but vary the quantity, in three identical clear containers or plastic bags.
Show students the first container and circulate it around the classroom so that they can familiarize themselves with the quantity and size of the objects.
Ask students to estimate the number of objects in the container and write their estimations on the board.
Empty the contents of the container and ask students to suggest ways to count the objects (for example, make groups of 2, 5, 10, 20, 25 or 50).
Count the objects and compare the total to students' estimations.
Ask students questions such as:
- Was your estimation close to the actual number of items in the container?
- What strategy could you use to get a more accurate estimation next time?
Show students the second container and ask them the following questions:
- How many objects do you think are in this container?
- Do you think it contains more or fewer objects than the first container?
- How can the number of items in the first container help you estimate the number of items in this container?
Ask students to explain their reasoning.
Empty the second container of its contents and begin counting the objects.
Stop after counting 10 objects and ask students if they want to change their estimation based on the amount of 10 objects.
Ask students who changed their estimations to explain their reasoning.
Continue counting the objects in the second container and compare students' estimations to the actual quantity.
Ask students the following question: Why are the estimations more accurate this time?
Discuss with students the use of a benchmark to make estimations: knowing the number of objects in a small set can help determine the number of objects in a larger set.
Finally, show students the third container and ask them to identify strategies that might help them estimate the amount of objects in the container.
Encourage students to use the strategies mentioned to estimate the number of objects in the third container.
Clarify to students that the goal of estimation is to obtain a number that is close enough to the actual number, not necessarily to determine the exact number.
Project Appendix 2Q.1 on the interactive whiteboard.
Give students sticky notes and ask them to write their name and estimation on them and stick them in the appropriate box on the board.
Count the contents of the third container and discuss the results with students. Emphasize that estimations are more accurate when benchmarks are used.
Active Learning (Exploration)
Duration: approximately 45 minutes
Group students into pairs.
Provide each student with a copy of Appendix 2Q.2.
Give each team a plastic bag of small objects. Each bag should contain enough objects to make it impossible to visually count them.
Ask students to estimate and count the objects in the bag and have them write both numbers on the worksheet (Appendix 2Q.2).
Ask teams to switch bags with another team when they are finished.
Encourage students to use a strategy that uses a quantity as a benchmark before estimating the total number of items in the bag.
Circulate around the classroom and observe how students proceed.
Ask students questions to allow them to explain the strategies used such as:
- What benchmark did you use to estimate the number of items in the bag?
- What other strategies can you use to estimate the number of items in the bag?
- How can estimating the number of items in one bag help in estimating the contents of another bag?
Consolidation of Learning
Duration: approximately 35 minutes
Bring students together for the discussion and ask them the following questions:
- How did you estimate the number of items in the bags?
- Was the quantity of items in some bags more difficult to estimate? Why or why not?
- What strategies did you use to count the objects?
- If the same bag contained larger items, would there have been more or fewer of them?
- If the same bag contained smaller items, would there have been more or fewer of them?
- What kinds of groupings can be made to estimate the quantity of objects?
Discuss with students opportunities for estimation outside of the classroom; for example, when making a recipe that calls for 50 caramels, what can be done to estimate whether a bag contains enough? Remind them to use 5 or 10 caramels as a benchmark to determine if the bag contains about 50 caramels.
Examples of Success Criteria
The student:
- uses the appropriate benchmarks;
- makes accurate estimations;
- explains their estimation strategies;
- uses strategies to count quickly;
- modifies their estimation based on what the student knows after counting a certain quantity.
Differentiated Instruction
The activity can be modified to meet the needs of the students.
To Facilitate the Task | To Enrich the Task |
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Source: translated from Guide d'enseignement efficace des mathématiques de la 1re à la 3e année, Numération et sens du nombre, p. 147-151.
Learning Situation 3: Mystery Bags
Total duration: approximately 3 hrs 30 min
Overall Expectation | Specific Expectations |
B1. Number Sense |
B1.1 Read, represent, compose, and decompose whole numbers from 0 to 200, using a variety of tools and strategies, in a variety of contexts, and describe the ways in which they are used in everyday life. B1.2 Compare and order whole numbers up to 200 in a variety of contexts. B1.3 Estimate the number of objects in collections of up to 200 and verify their estimates by counting. B1.4 Count to 200, including by 20s, 25s, and 50s, using a variety of tools and strategies. B1.5 Describe what makes an number even or odd. |
Learning Goals
The purpose of this learning situation is to allow the student to:
- decompose numbers up to 200 into hundreds, tens, and ones;
- exchange ten 10s for a hundred;
- represent numbers using base ten and other materials;
- describe the relationships between numbers.
Learning Context | Prerequisites |
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By the beginning of Grade 2 , the student is able to construct the concept of place value. For example, the student may see the number 33 as representing 33 ones or 3 tens and 3 ones or 2 tens and 13 ones. In addition, the student has addressed the regularity of addition by 10 and should be able to mentally add 10 to 33 without counting. In Grade 2, students will be expected to understand that in any number up to 200:
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In this learning situation, the student should be able to:
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Materials
Main Activity
- reusable plastic bags
- mystery bags containing identical objects (one per team of two)
- appendix 2Rep.1 (Mystery Bag) (one copy per pair)
- appendix 2Rep.2 (Sample Centre Organizer)
- annex 2Rep.7 (Countdown to Zero Anecdotal Record)
- large sheets of paper
- felt-tip pens
In each centre
- sheets of paper or math journal
- calculators (optional)
Centre 1: The Teacher's Helpers
- appendix 2Rep.3 (The Teacher's Helpers) (one copy per student)
- manipulatives: interlocking cubes, centicubes (small cubes of 1 cm3), counters
Centre 2: The Countdown
- appendix 2Rep.4 (Place Value Mat) (one copy per pair)
- base ten materials: unit cubes, rods, and flats
- sets of number cards from 1 to 9 (several)
Centre 3: Mystery Numbers
- interlocking cubes
- cards (one per student)
- paper bags (one per student)
- stapler
Centre 4: The Number Wheel
- appendix 2Rep.5 (Spinning for a Flat)
- appendix 2Rep.4 (Place Value Mat) (one copy per student)
- paperclips or arrows for spinners
- base ten blocks
- appendix 2Rep.6 (Reflection Stems) (one copy per student)
Mathematical Vocabulary
hundreds, tens, ones, represent, value, place value, group, regrouping, trade
Before Learning (Warm-Up)
Duration: approximately 40 minutes
The Mystery Bags
Prepare enough mystery bags for each team to have one. Each mystery bag should contain between 50 and 200 identical objects (for example, 148 pattern blocks, 63 counters or 142 sticks). Using a variety of objects that vary in number and size provides students with different experiences in working with the different bags.
Begin the activity by telling students that several mystery bags containing a variety of different objects have been left in the classroom and that they need to determine the quantity of objects in each bag.
Group students into teams of two. Give each team a copy of Appendix 2Rep.1.
Explain to students that they will need to:
- estimate the quantity of objects contained in each bag;
- explain how they arrived at this estimation.
- determine the exact number of objects in their bag using the counting strategy of their choice (for example, students can count objects by 1 or in increments of 2, 5, 10, 20, 25, and 50).
Circulate around the classroom as students work and observe the counting strategies that teams use.
Assist students who are struggling by asking questions such as:
- What strategy did you use to count the objects?
- How many objects are there?
- How can you prove it?
- Is there another way to count objects? What is it?
- Is there an easier way to count objects? What is it?
Bring students together to share their findings.
Support teams as they share their counting strategies with the class.
Ask each team:
- to identify the objects in the bag;
- to indicate the estimation made;
- to explain how the team made their estimation;
- identify the counting strategy used;
- to specify the actual number of objects in the bag;
- to explain why the team is satisfied or not with their estimation.
Highlight effective counting strategies that students have used (for example, counting by 1 is not effective because it is too long and easy to make mistakes) and list them on a large sheet of paper for reference in future activities.
Active Learning (Exploration)
Duration: approximately 2 hours
Organize four learning centres in advance.
Explain to students that they will be doing four different activities involving place value.
Group students into four teams.
Using Appendix 2Rep.2 as a guide, prepare a chart showing the activities and rotation schedule for the teams.
Gather the materials needed for each activity and place them in separate bins. Label each bin with the activity name and number.
Prepare a checklist for each activity indicating the success criteria. Attach each checklist to a clipboard and place it in the corresponding centre. Use Appendix 2Rep.7 as a guide.
Designate the area of the classroom reserved for each activity, by grouping desks or reserving a table or corner.
Introduce students to the activities one at a time: state the name of the activity, explain the work to be done, show the materials, and model the activity as needed.
Tell students that they will be observed while working in a one of the centres.
Accompany students to the centre being evaluated and use the list of established criteria to evaluate each team member.
Note: It is important that students understand the numerical value of the ones units, tens rods, and hundreds flats that are part of the base ten materials before undertaking the activities that require these materials. If they do not, have them use interlocking cubes or centicubes to complete the activities.
Centre 1: The Teacher's Helpers
Give each student a copy of Appendix 2Rep.3 and read the problem aloud.
The teacher needs more students to help organize a party. Make a list of students from the class that could help. Write the names of the students in the box provided. Assume the teacher already has 25 students. How many helpers will there be if the teacher chooses all students you have listed? Write down on a piece of paper the counting strategy you used to determine the number of students who will help organize the party.
Have students use the manipulatives and solve the problem.
Centre 2: The Countdown
Explain to students that they will play a game in which they will subtract from 100 (a hundreds flat) down to 0. The first team to reach 0 will be the winning team.
Inform students that they will work in pairs and play one group against the other.
Provide each group with a copy of Appendix 2Rep.4, base ten materials, and several decks of number cards from 1 to 9.
Invite students to place the cards between the two groups, face down on the table and to place a hundreds flat on their place value mat before beginning the game.
Have each student take a card and work with their partner to add up the numbers on them.
Ask students to subtract this number from their hundreds flat, by exchanging the flat for tens rods and the rods for ones units and represent their new number on their place value mat.
Example
One group randomly draws cards 2 and 6 and add these two numbers and to get a total of 8. They trade their hundreds flat for tens rods. Students should notice that it is still impossible to remove 8 from a rod. Therefore, they need to trade one rod for ten units. Students can now remove the 8 units, giving them 92 on their place value mat.
Have students place the cards they have picked up, face down on the table, next to the deck when the group is finished.
Invite students to shuffle the cards and reuse them if they run out before one of the groups reaches zero.
Centre 3: Mystery Numbers
Ask students to:
- choose a mystery number from 100 to 200, then represent it using base ten materials (hundreds flat, tens rods and ones units);
- write at least three clues on an index card to help the class detectives discover the mystery number.
Example
If a student chooses 142, the clues may be as follows:
- I have 7 items in my bag.
- The number is made up of an odd digit and two even digits.
- The tens digit is higher than the ones digit.
- The tens digit is 1 more than 3.
Invite students to put the flat, rods, and units representing the mystery number into a paper bag and staple the clues to the bag.
Ask students to exchange their bag with a partner. Each student should try to figure out their partner's mystery number. The bags can be stored at the centre so that other classmates can try to solve them.
Centre 4: Spinning for a Flat
Use the template in Appendix 2Rep.5 to prepare spinners on cardboard. Laminate them and add arrows or paperclips to them before putting them in the bin.
Provide each student with a copy of Appendix 2Rep.4.
Have students take turns spinning the arrow on the spinner and, depending on where it stops, they receive a unit cube or rod to place on their place value mat.
Invite students to continue spinning the arrow and tell students to add the appropriate base ten material to their place value mat depending on the number the arrow stops on.
Ask students to exchange ones for tens whenever they can and to say the new number each time.
Continue the game until one student reaches 100 and exchanges their 10 tens for a hundred. As an extension, continue until the student reaches 200, which means the student can trade 20 tens for two hundreds.
Consolidation of Learning
Duration: approximately 40 minutes
Bring students back together when all groups have completed the four activities.
Ask them to share their discoveries and challenges and suggest tips to make the games easier.
Ask students questions to help them express themselves more accurately about the place value, such as:
- What did you learn about the usefulness of grouping when it comes to counting?
- What have you grouped into tens?
- What have you grouped into hundreds?
- How did the manipulatives help you?
- What grouping strategies did you use to facilitate the activity?
- How did trading ones for tens help you determine the total?
- How did trading tens for hundreds help you determine the total?
Provide each student with a copy of Appendix 2Rep.6 and invite them to select a few sentences to complete to record their thoughts in their math journal. This can be done individually or in groups of two or four.
Examples of Success Criteria
The student:
- exchanges ones for tens at the appropriate time;
- names the new numbers;
- represents numbers using manipulatives;
- describes their work in their math journal using appropriate mathematical vocabulary.
Differentiated Instruction
The activity can be modified to meet the needs of the students.
To Facilitate the Task | To Enrich the Task |
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Ask the student to create their own place value game based on what they have done, or invent a new one. |