Calculating Dietary Energy · seed 1 · A4, ink-friendly. The answer key prints on its own page for grown-ups.

Calculating dietary energy

Science · Organisms & Life Processes · ages 11-13
Name ______________________   Date ____________

  1. Kilocalories (kcal) and kilojoules (kJ) are two different units for measuring the same thing: energy in food.

    Circle one:   True   False

  2. A juice bottle label shows 'Energy: 420 kJ / 100 kcal'. Which number is measured in kilojoules?

    • 420
    • 100
    • Both numbers show kilojoules

  3. Who is likely to need more energy in a day: someone reading quietly all afternoon, or someone training hard for football practice?

    • The reader
    • The football player
    • They need exactly the same amount

  4. Jess is 12 and trains for gymnastics five days a week. Compared with a same-age friend who does no sport, is Jess's daily energy requirement likely higher, lower, or about the same?

    • Higher
    • Lower
    • About the same

  5. A cereal bar label shows 'Energy: 800 kJ' per bar. Using about 4 kJ for every 1 kcal, roughly how many kcal is that?

    Answer: ______________

  6. Look at the bar chart of energy in three lunches. Which lunch has the most energy?

    Lunch A450Lunch B700Lunch C550
    • Lunch A
    • Lunch B
    • Lunch C

  7. Breakfast, lunch and dinner added up to 350, 600 and 700 kcal, plus a 150 kcal snack. If the daily guide is about 2000 kcal, how many kcal short of that guide is this total?

    Answer: ______________

  8. Priya's meals and snacks today added up to about 2600 kcal. Her rough daily guide is about 2000 kcal. What does this tell you about her energy today?

    • Her intake exactly matches her needs
    • She has an energy deficit
    • She has an energy surplus
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Answer key

For grown-ups. Fold this page away before handing over the rest.

Calculating dietary energy W1-mt_83KkBCtVyR-s1

  1. True · Food labels often show both units together because some countries use kJ and others use kcal.
  2. 420 · kJ is always the bigger number on a label because one kcal is about 4 kJ. Here that number is 420.
  3. The football player · Moving and exercising burns extra energy, so an active body needs more fuel from food.
  4. Higher · More training means more energy used, so Jess's body needs more fuel than a less active friend's.
  5. 200 · Divide the kJ number by about 4: 800 divided by 4 is 200 kcal.
  6. Lunch B · Lunch B has the tallest bar, so it has the most kcal of the three.
  7. 200 · Add the meals and snack: 1800 kcal in total, which is 200 kcal below the 2000 kcal guide.
  8. She has an energy surplus · 2600 kcal is more than her 2000 kcal guide, so she took in more energy than she used: a surplus.
Worksheet · LightMySky