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Natural sciences

Grade 4

Energy and change

Module 31

Food as a source of energy


To discuss and describe food as a source of energy

[lo 1.1, 1.2, 1.3]

We have to take in food to obtain energy, and eat enough to keep going for long enough. If we do not eat enough, our bodies will not remain warm and we will not have enough energy to do our daily work. To remain healthy, we have to follow a balanced diet. It is possible to know whether you eat correctly and get enough to eat by studying the information on the boxes, packets, bags and tins in which food is bought to find out how much energy per volume is contained in the foodstuff. The quantity that is eaten is measured in kilojoules.

Some of the energy that animals obtain from the food that they eat is stored in their muscles. Those muscles are able to use the energy to do work.

In early times, people used the energy of their own muscles to do work, like gathering food, tilling their fields and building shelters. They made simple implements to help them use this energy more efficiently and to work better. The first tools were made of wood and stone, but when people discovered how to melt down metals, they used metal to make better and stronger tools.

They also discovered that they could use animals to work faster and better and get more work done, as one ox is able to do the work of eight grown men.

Animals were used to transport people and goods, to pull the ploughs in the fields and to pump water from below the ground to irrigate the fields.

Work out a balanced diet by examining the labels on different containers in which food is packed.

  • Learners must be divided into three groups: Group 1 must determine the kilojoules value of breakfast; Group 2 the kilojoules value of lunch; and Group 3 the kilojoules value of supper.
  • Each group must then report their findings concerning the value of the specific meal with regard to the energy requirement for the day.



The learner will be able to act confidently on curiosity about natural phenomena, and to investigate relationships and solve problems in scientific, technological and environmental contexts.

Assessment Standard

We know this when the learner

  • plans investigations;
  • leads investigations and collects data;
  • evaluates data and provides feedback on observations.



This assignment involves research. Help the learners to plan their research, to collect information, to draw conclusions and to communicate their findings.

Questions & Answers

how to know photocatalytic properties of tio2 nanoparticles...what to do now
Akash Reply
it is a goid question and i want to know the answer as well
Do somebody tell me a best nano engineering book for beginners?
s. Reply
what is fullerene does it is used to make bukky balls
Devang Reply
are you nano engineer ?
what is the Synthesis, properties,and applications of carbon nano chemistry
Abhijith Reply
Mostly, they use nano carbon for electronics and for materials to be strengthened.
is Bucky paper clear?
so some one know about replacing silicon atom with phosphorous in semiconductors device?
s. Reply
Yeah, it is a pain to say the least. You basically have to heat the substarte up to around 1000 degrees celcius then pass phosphene gas over top of it, which is explosive and toxic by the way, under very low pressure.
Do you know which machine is used to that process?
how to fabricate graphene ink ?
for screen printed electrodes ?
What is lattice structure?
s. Reply
of graphene you mean?
or in general
in general
Graphene has a hexagonal structure
On having this app for quite a bit time, Haven't realised there's a chat room in it.
what is biological synthesis of nanoparticles
Sanket Reply
what's the easiest and fastest way to the synthesize AgNP?
Damian Reply
types of nano material
abeetha Reply
I start with an easy one. carbon nanotubes woven into a long filament like a string
many many of nanotubes
what is the k.e before it land
what is the function of carbon nanotubes?
I'm interested in nanotube
what is nanomaterials​ and their applications of sensors.
Ramkumar Reply
what is nano technology
Sravani Reply
what is system testing?
preparation of nanomaterial
Victor Reply
Yes, Nanotechnology has a very fast field of applications and their is always something new to do with it...
Himanshu Reply
good afternoon madam
what is system testing
what is the application of nanotechnology?
In this morden time nanotechnology used in many field . 1-Electronics-manufacturad IC ,RAM,MRAM,solar panel etc 2-Helth and Medical-Nanomedicine,Drug Dilivery for cancer treatment etc 3- Atomobile -MEMS, Coating on car etc. and may other field for details you can check at Google
anybody can imagine what will be happen after 100 years from now in nano tech world
after 100 year this will be not nanotechnology maybe this technology name will be change . maybe aftet 100 year . we work on electron lable practically about its properties and behaviour by the different instruments
name doesn't matter , whatever it will be change... I'm taking about effect on circumstances of the microscopic world
how hard could it be to apply nanotechnology against viral infections such HIV or Ebola?
silver nanoparticles could handle the job?
not now but maybe in future only AgNP maybe any other nanomaterials
I'm interested in Nanotube
this technology will not going on for the long time , so I'm thinking about femtotechnology 10^-15
can nanotechnology change the direction of the face of the world
Prasenjit Reply
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
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Source:  OpenStax, Natural sciences grade 4. OpenStax CNX. Sep 18, 2009 Download for free at http://cnx.org/content/col11096/1.1
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