Fun with Numbers   K. KARTHI & C. SASIKUMAR

Making numbers concrete...                               CBSE, Mathematics, Class 3, Unit 2

Objectives

• To recollect the understanding of the concepts of addition, subtraction and visual estimation of 2-digit numbers.
• To introduce the concept of 3-digit numbers and place value.
• To enhance Mathematisation of the child's thinking.

ENGAGE

I)    Work with pebbles/beads (Addition & Subtraction)

1. Group children into groups of 4-5. (The teacher could   form   the   groups in a manner that there is at least one student who can provide peer  support to the others while the teacher is going around supervising the activity)
2. Place a bunch of pebbles (or beads, seeds) in front of  different  groups. Also give  them a box of spare pebbles (or beads, seeds)  that  will  be used later in the activity.
3. Children could be  given  a few  tasks step by step:

1. Count the number of objects.
2. Remove 7 objects from the group and find the no. of remaining objects
3. Add 12 objects and find the revised number of objects …and so on
4. Teacher' s role - The teacher needs  to  go  around  in  the    groups a n d a s k s t u d e n t s h o w t h e y arrived at the answer. If they are counting the remaining objects, the teacher  can  help  them  do  it  by t h e   p r o c e s s    o f    a d d i t i o n / s u b t r a c t i o n u s i n g a p a p e r and pencil
5. At the end, a bunch of pebbles/beads could be kept and one volunteer student in every group could be asked to guess the total quantity without counting. Other students in the group could verify.

[Since the students have learnt the numbers 1-99 in their previous standard, this will help the students to test their prior knowledge and participate in theclassroomactivities]

II)    Stick game (or) Beads in a string:

Ensure that students are familiar with stick (beads) and rubber band (string) to represent 2-digit numbers. Eg.

• 43  is  made  with  4  bundles  of  tens   and 3 singles (refer image below)
• Similarly 74 is made with 7 bundles of tens and 4 singles
• 51 is made with 5 bundles of tens and 1 single.
• 99 is made with 9 bundles of ens and 9 singles.
• Give them practice with some more  2 digit numbers.

EXPLORE

I) Stick game (or) Beads in a string:

As an extension of the previous activity, to represent 3-digit numbers.

Eg.

1. 43  is  made  with  4  bundles  of  tens     and 3 singles.
2. 243 is made with 2 groups of 10 bundles of 10 (i.e. a hundred group), 4 bundles of tens and 3 singles.
3. 243 is made with 2 groups of 10 bundles of 10 (i.e. a hundred group), 4 bundles of tens and 3 singles.
4. Then ask the students to  make  243 using only bundles of tens and  singles (i.e. 24 bundles of tens and 3 singles)
5. Give them practice with other 3-digit numbers.

As an extension  of  the  previous  activity, now students  will  be asked  to  make  3 digit numbers and their expanded form.

II)    Units Tens Hundreds (UTH) Activity:

Ensure  that   students   are   familiar with UTH to represent numbers.

et us make it a little more interesting with reater numbers. Let the students explore other umbers. Teacher has to guide students ppropriately.

EXPLAIN                                              

Start with debriefing of the activity carried out using stick bundles / beads. Students could share their experiences and difficulties faced.

Number expander activity:

By now, students are probably in position to explain a 3-digit number. They also need to read and write. For this, the number expander activity will be useful.

Since number expander activity gives hands-on experience for students, it will be useful for them to relate the 3-digit concepts with their prior knowledge and improve their thinking capacity.

Note to Teacher How to make number expander:

1. Take  a long  strip  of chart, divide  it into 6 parts and mark as (Hundreds /Tens/Ones) in the piece of chart as shown below.
2. Write a 3-digit number as shown below

3. Fold  the  chart  so  that  Hundreds  Tens and Ones are hidden as shown below

4. Now, students will unfold the chart to see the number with Hundreds, Tens and Ones. It coulde unfolded in the following ways tell this verbally without writing the number)

4. How will the shopkeeper write the amount in the bill? (Students could be asked to write the amount in number and words like how they usually do in bills)
5. Now, you pay for the item (Demonstration / role play could also be done using currencies – hundred rupee notes, ten rupee notes and one rupee coins)

EVALUATE

Teacher can use oral and written tests to evaluate students understanding of the concept.

To Download the Teaching Learning Material(TLM), Please click the link: Teaching Learning Material