Towards a just, equitable, humane and sustainable society

# Measurements in Real Life

Science is an endeavor to understand the world around and it is impossible to explain it without mathematical expressions. From fundamentals, such as length, mass and time to more complex ones such as the speed of light and rate of radioactivity, science attempts to measure every phenomena observed. Hence, measurement is intertwined with understanding concepts of science. The content in the syllabus follows a similar progression from fundamental units in class VI, to derived units like area, volume and density in class VII. Class VIII deals with more complex measurements like temperature. It is necessary for students to learn the fundamentals of measurement and develop the skills for precise measurement in the early classes so that the transition to more complex topics is smooth. This article presents ideas on how to concretize this concept by dealing with measurement of real life objects. The aim is to give the students experiences such that learning becomes fun.

LENGTH

Nonstandard and standard units of measurement – As a refresher of what the students have learnt in previous classes, the teacher can revise the need for standard units of measurements. A simple activity will help the students appreciate this. Divide them into groups and assign each group a different object and unit to measure. Each student in that group has to measure it using the non-standard unit.

 Activity Measurement made by every child in the group Measurement made by every child using scale / Ruler Measuring a thread ( in cubit ) Measuring length of the table ( in handspace ) Measuring length of the classroom ( using foot length )

This will reveal that none of these measure- ments gives the same magnitude. Point out that non-standard measurement is inconsistent and not reliable. Hence arose the need for standard units of measurement, which is done using simple equipment like scale, measuring tape etc. Each student is then asked to measure the same object now using a scale/tape and note their readings… What difference do they observe?

A feel of a meter - To get the feel of a meter, students can find out how tall, long and wide 1m is  using  a  meter  stick.  They  can  stand  and  mark  where  the  meter  stick  touches  their  body  to measure   how   high   it   is;   using   arm   length   measure   how   long   it   is   and  likewise   measure how  wide  it  is.  After  each  child  has  experienced  their  individual  sense  of  measurement  of one meter, they can be asked to estimate the  ength of various objects. This will help enhance their abilities to estimate measurement accurately.

 No Task Estimate (m) Measurement (m) Difference between the two 1 Height of the door knob 2 Height of the door 3 Length of the blackboard 4 Distance from the point you are standing to the wall 5 Width of the blackboard

Understanding sub-multiples of units.

It is a bit abstract and difficult for students to comprehend the magnitude in powers of ten. They also  need  to  understand  why  different scales  are  used  to  measure  different  objects.  An  eraser is  not  measured  in  kilometers  and  neither  is  the  distance  between  two   cities  measured  in  cms. After   the   scale   has   been   learnt   and   in   order   to   make   this   more   visually   striking   for students, they  can be asked to depict 1mm, 1cm, 1m, 1km using a thread/tissue roll/ribbon.

P.S.: This can be extended to mass as well. Ask students to predict the weight of objects – ranging from light to heavy.  Using objects that they regularly use will be more effective for such an assignment.

AREA

When we describe the area of something, we are stating how many squares of a given size it takes to cover the surface.

Using a square/grid/cube that has dimensions 1cm*1cm, ask students to measure the area of surfaces such as the textbook, a chair, a photograph etc. The number of squares counted is the area of the surface. This can be used to measure the area of irregular shapes as well.

Give two shapes, a square and a rectangle, and ask students to compare and find which one has a bigger area.Once they are familiar with      area, make students measure the area of different surfaces and express it in all the units – mm2, cm2 and m2.

Formula Derivation

Ask students to measure various rectangles and fill in the following table.

Students find the area using the grid/cube. l*b is found by multiplying the sides. Ask students to show the relationship between the length*breadth and area of the rectangles in the table in the form of a formula. From this, the teacher can facilitate the discussion on formulas to find areas of different shapes.

VOLUME

We all know that the space occupied by an object is called its volume. So what does  that  mean.An  object  occupies  space  both  on  the  ground  and  in  the air - what we call height. Hence the generic formula for volume is base area height.

To give students a sense of estimating volume, use graduated syringes/measuring cylinders to measure 1mL, 5mL, 10mL, 50mL, 100mL,     and 1L of water. Replace the same with grains of rice. This will be the solid equivalent of the liquid. Now ask them to estimate the volume of   a bottle/jug and a medium sized freezer container. What is the difference between the estimated and actual value?

 No Object Estimate ( mL) Measurement ( mL) Difference between the two 1 Bottle / Jug 2 Medium sized freezer container 3 Paper cup / Tea cup 4 Juice can 5 Cough syrup bottle

Students  explore  the  concept  of  density  through  the  familiar phenomena of sinking and floating. Begin by using two objects - a small rock and a wooden block. The rock used in the demonstration should be smaller  and  lighter  than  the  wooden  block.  Ask  students,  which  is heavier, the rock or the wood. Ask them to predict which will sink and which will float. Then, place the rock and the wooden block in water.

Students  realize  that  there  must  be  something  more  to  sinking  and floating  than  size  or  weight.  Help  students  arrive  at  the understanding  that  the  relationship between   the   weight   of   the   object   and   its   size   is   important.   Let   students   know   that   this relationship,  between  the  weight  of  an  object  and  its  volume  (the  amount  of  space  an  object takes up), is called density.

They investigate further by using the water displacement method to find volumes of water equal to a block of wood and a rock. After comparing the weight of each object with the weight of an equal volume of water, students can generalize an important rule about sinking and floating: Objects that are less dense than water float, and objects that are denser than water sink.

Use   different   liquids   (liquids   denser   than   water   like   honey,   corn syrup and lighter than water like iso-propyl alcohol, vegetable oil) and observe  the  sinking/floating  behavior.    This  can  be  used  as  a  starting point to discuss the fact that liquids also have varying densities… Children can make a liquid density column to see the arrangement of liquids according to their densities. Drop different objects in these to see which of them float and sink in which liquid.

 Win exciting prizes Encourage students to try out these activities and share any interesting observations that you come across to win exciting prizes. Entries can be sent to       Azim Premji Foundation No 5, Nessa Illam, Opposite to RTO, Mudaliarpet,  Puducherry - 605004

R. Jamuna

TGT, TPGHSS Ariyankuppam

Start Date:
Wednesday, May 10, 2017 - 09:30
End Date:
Thursday, June 22, 2017 - 18:00
Subject:
Science