Discussion Questions and Activities for Ocean Sunlight

Discussion Questions

For all students:

  1. What are phytoplankton and why are they so important to life in the oceans?
    How are phytoplankton similar to plants on land?
  2. Do phytoplankton live both at the surface and the bottom of the ocean? Why or why not?
  3. How do phytoplankton reproduce? How long does it take for them to double in number?
  4. How much of the oxygen in our air comes from phytoplankton? How much from the plants on land?

For older students:

  1. What do animals who live in the deep ocean eat? Where does the energy in that food come from?
  2. Phytoplankton need a supply of nutrients (“fertilizer”) to grow. How does that supply of nutrients get recycled into the sunlit surface waters?
  3. Does sunlight-energy get recycled? Why or why not?
  4. When you eat fish, where does the carbon and energy in your food originate?
  5. The questions above can help meet Common Core Anchor Standards R.1,2,3,4,7,10; SL.1,2

Grow Your Own Phytoplankton
Phytoplankton live in all bodies of water, but only when their population grows and they become dense will the water appear green. Collect some pond water (or puddle water) and put it in one-cup containers. Add 1-5 drops of Miracle Grow plant fertilizer and place the rest of the containers on a windowsill or next to a light. At the same time, place the same number of containers in a dark closet. Wait a week or two and observe what happens with each set of containers (note: the water in the containers near light should turn green). Ask students to explain how sunlight affected the phytoplankton.

This activity can help meet Common Core Anchor Standards W.1,7; SL.1

Phytoplankton Population Boom
This exercise will help students understand how quickly phytoplankton can grow.
Put students in pairs and give each pair a bag of dried peas. Remind them that phytoplankton reproduce by splitting in two over the course of about a day. Start with one pea and let it divide to make two over a virtual day by taking another pea from the bag and placing it next to the first one. Then let those two “divide” to make four over the next virtual day by laying out two more peas. Then “divide” each of those and continue doing this for another few virtual days. Ask students how many phytoplankton they would have after five days.
To illustrate how this feeds the food chain, have one of the students be a zooplankton and start “eating” (removing) the “new phytoplankton” (only the phytoplankton produced in that “day”). This will demonstrate how the numbers of “phytoplankton” remain stable while still feeding up the food chain.

This activity can help meet Common Core Anchor Standards W.7; SL.1


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