العلوم (بالإنجليزية) الصف الخامس الابتدائي، الأسبوع 17: Ponds, rivers and salty seas

Earth’s spheres and watery homes

الأسبوع 17 · المحور الثالث «حماية كوكبنا»، الوحدة الثالثة «الموارد الموجودة على سطح الأرض»، المفهوم 3.1 «التفاعلات بين الغلاف الحيوي والغلاف المائي» (ب): أغلفة الأرض والأنظمة المائية · 3 دروس

Ponds, rivers and salty seas

Discovery Education Science P5: Term 2, Unit 3, pp. 20–26

GoalCompare pond, stream, river, estuary, saltwater lake and sea ecosystems, and write a claim, evidence and reasoning about water’s impact on life.

New words

aquatic ecosystem · a community of living things and the water they live inestuary · the place where a river meets the seasalt water · water with a lot of salt in it, as in the sea

Explanation

An aquatic ecosystem is a water home with the living things in it. There are freshwater ecosystems and saltwater ecosystems. A pond has still fresh water, where water lilies grow and frogs and insects live. A stream is small, cool fresh water that flows fast. A river is a larger flow of fresh water that runs to the sea, like the Nile. An estuary is where a river meets the sea, so fresh and salt water mix, as where the Nile meets the Mediterranean. A saltwater lake, such as Lake Qarun in Fayoum, has salty water, so only animals suited to salt water can live in it, and Nile fish that need fresh water cannot. The sea is salty and has waves and currents, and the Red Sea has coral reefs full of fish. The type of water and how it moves decide which living things can survive there. A sea fish cannot live in a pond, and a pond frog cannot live in the sea.

Ecosystem	Water	Movement	Life found there
pond	fresh	still	water lilies, frogs, insects
stream	fresh	fast, cool	small fish, moss
river	fresh	flows to the sea	fish, reeds, birds
estuary	mixed	river and tide meet	crabs, birds
saltwater lake	salty	still	animals suited to salt water
sea	salty	waves, currents	coral, fish, turtles

Worked examples

Clues	Ecosystem
still fresh water, lilies, frogs	pond
cool fresh water running fast over stones	stream
salty, waves, coral reef	sea

Clues point to an ecosystem. Still fresh water, water lilies and frogs mean a pond. Salty water, big waves and coral reefs mean a sea.

A sea scene. Fish, a turtle and coral live together in the salty water of a warm sea. These animals are suited to salt water, and they could not survive in a freshwater pond.

Part	What it says
Claim	Water supports life, and different kinds of water support different living things.
Evidence	Frogs live in ponds, and coral and turtles live in the sea.
Reasoning	Each animal is suited to its kind of water, so a change in the water changes who can live there.

A scientist’s explanation about water’s impact. The claim answers the question, the evidence gives facts, and the reasoning links them.

Class activity

Ecosystem cards (a grown-up helps). Make six cards, one for each kind of aquatic ecosystem. On each card write the type of water, how it moves and two living things found there. If you can visit a park pond or the seaside with a grown-up, watch from the bank or the beach and never touch or take water from canals or drains.

Practice

Name one freshwater ecosystem and one saltwater ecosystem.

What is an estuary?

A place has still fresh water, water lilies and frogs. Which ecosystem is it?

Why can a sea fish not live in a freshwater pond?