الأسبوع 9 · الفصل 7 «السلسلة الغذائية»: 7-1 السلسلة الغذائية، 7-2 الكائنات الحية والهواء والماء · 3 دروس
2
Arrows show where the energy goes
Science P6: Term 1, Chapter 7, pp. 62–67
GoalUse arrows correctly: they point from the food to the eater and show how energy moves.
New words
energy · what living things need to move and to growarrow · in a food chain, it points from the food to the animal that eats itconsumer · a living thing that eats other living things
Explanation
Arrows in a food chain have a rule: they point from the food to the eater. The arrow shows the way that energy travels. In grass → grasshopper → frog, the grass gives energy to the grasshopper, and the grasshopper gives energy to the frog. So the arrow points to the one that eats. A good way to read it is “is eaten by” if you read the arrow backwards. In a chain, the plant at the start gets its energy from sunlight. Animals cannot make their own food, so they get energy by eating. Wheat → mouse → snake → eagle is a chain with four living things. If you take away one link, the other living things are affected.
Worked examples
Drawing
Right or wrong?
eagle → snake
wrong
snake → eagle
right
Mariam draws: eagle → snake. Her teacher says the arrow points the wrong way, because the snake is the food and the eagle is the eater. The correct arrow is snake → eagle.
Seif reads the chain wheat → mouse → snake → eagle and answers: the wheat is the producer, the mouse is a herbivore, the snake and the eagle are carnivores.
What if the snakes disappear from a field? The mice would eat more wheat, and the eagles would lose some of their food. A change in one link affects the others.
Class activity
Arrow check. Draw four chains on cards with arrows: two correct and two with an arrow pointing the wrong way. Swap with a partner and find the mistakes. Fix them. Use only the arrow rule: the arrow points from the food to the eater.
Practice
1
Which way does an arrow point in a food chain?
From the food to the eater.
2
Where does the energy at the start of a chain come from?
From sunlight, through the plant.
3
Is this chain correct: fox → rabbit → grass? Explain.
No. The arrows are reversed; it should be grass → rabbit → fox.
4
In wheat → mouse → snake → eagle, which is the producer?
