Marine primary producers play a crucial role in the functioning of marine ecosystems. No, they don’t bite and you won’t see any cool videos of them swimming around in the ocean, but you better believe they are important. From the smallest Sybiodinium to the largest kelp, marine primary producers form the base of the food chain and provide energy to the higher trophic levels. So even though they may not seem super cool to your students at first glance, you can definitely change their opinion with these activities for your marine plants, phytoplankton and algae lesson.

Seaweed Scavenger Hunt

  First off, you need to make sure that your students understand that algae and seaweed are the same thing. After you have done that, you can start off with one of my favorite activities: Seaweed Scavenger Hunt.   You’ll need to give yourself and your students a few days to a week to prep this one. Have your students bring in empty containers with ingredients listed on the back. This can be food, makeup products, cleaning products, lotions, hair care, etc. As long as it has ingredients listed, it’s good!   Once you have a good collection of containers, spread them out around the room. Your students will be given a designated amount of time ( I usually gave about 15 minutes) to hunt for items that had one of the following ingredients in it.  

1. Carrageenan
2. Algin
3. Agar
4. Alginate

  Once they have completed their scavenger hunt, you can have students raise their hands and talk about the items they found with those ingredients. That’s when you tell your students that these ingredients come from seaweed, or algae. They look at you a little crazy and you may hear a few students yell “ewwwww” but it’s worth it. You can grab the free seaweed scavenger hunt activity by clicking here. It is also included in the free resource library.   As a little bonus, you can give your students a seaweed snack so they can actually eat some seaweed while you move on with your lesson. Some love it and some hate it! You can grab some seaweed snacks in bulk here (affiliate link). .

Show them different types of Algae

If you live in a coastal area, bring some in to show your students! Let them see different types under a microscope and discuss the importance of those types of plants and seaweed to the marine ecosystem.  

Make their Own 3D Phytoplankton

Often, phytoplankton and other marine microbes have some crazy shapes. Have students model them out of play dough or modeling clay. They can discuss the advantages of their structure and their role in the marine ecosystem. You can also use recyclable materials in place of clay or play dough.  

Phytoplankton Model

NOAA has a Phytoplankton Model that shows chlorophyll concentrations across the globe. These concentrations show where primary production is occurring and where nutrients are rich in the surface waters. This can be used as an activity for students to see where primary production is occurring and critically think about why production is higher in some places rather than others.

Algal Blooms

Discussing algal blooms is a great way to talk about human impact and how you can have too much of a good thing. Algae is essential for marine life but what happens when there is too much of it? Is it harmful? How do they affect the marine ecosystem? In this activity, a short reading on algal blooms is included as well as some questions students can answer about algal blooms.