Assignment ideas to support phenomenon-based · a. Omega-3 fatty acids are necessary to the body. The human body cannot make them on its own and must get them from food. b. There

Assignment ideas to support phenomenon-based learning

If a family of four eats fried Baltic herring steaks once a month, how much phosphorus is removed from the Baltic Sea in a year? A traditional Baltic herring steak consists of two Baltic herrings and it is assumed that each person eats two steaks. On average, one Baltic herring weighs around 75 g.

1 g phosphorus = 1 kg algae

1 kg Baltic herring = 4 g phosphorus

1 kg bream = 7 g phosphorus


Model answer:

One family dinner of Baltic herring steak takes up 4 x 4 = 16 Baltic herring

Annually, this amounts to 12 x 16 = 192 Baltic herring

Total weight of the Baltic herring used: 192 x 75 = 14,400 g = 14.4 kg

Amount of phosphorus removed from the sea: 14.4 x 4 = 57.6 g

The amount of phosphorus removed from the Baltic Sea by the family is 57.6 g.


Learn to recognise our local fish:a) b)c)

Model answer:a) roach b) bream and c) Baltic herring


If your school menu includes Archipelago Fish Patties once a month, how much algae does your school remove from the Baltic Sea in a month? Find out how many pupils there are in your school. Making one Archipelago Fish Patty (100 g) takes about 175 grams of caught and ungutted bream, and it is assumed that one pupil eats one patty.

1 g phosphorus = 1 kg algae

1 kg Baltic herring = 4 g phosphorus

1 kg bream = 7 g phosphorus


Model answer:

The school has about 600 pupils, for example.

This means that 600 fish patties are eaten in a month.

The patties take up 600 x 175 = 105,000 g = 105 kg

Amount of phosphorus removed from the sea: 105 x 7 = 735 g

Amount of algae removed from the sea: 735 kg

Eating Archipelago Fish Patties helps remove 735 kg of algae from the Baltic Sea each month. This corresponds to around 74 buckets of algae.


“By eating bream and Baltic herring twice a week, you can remove 14 buckets of blue algae from the Baltic Sea each year.”

a. Give an example of a food chain through which phosphorus is removed from the Baltic Sea through you.

b. Phosphorus makes up about 1.5% of a person’s weight. Why do humans need phosphorus?

c. Some of the phosphorus in the bream and Baltic herring you eat remains in your cells and tissues. Some is flushed down the toilet in your urine and faeces. How can we prevent this phosphorus from ending up back in the Baltic Sea?


Model answer:

a. Microscopic algae consume phosphorus from the water and use it to make phosphorus compounds (e.g. DNA). An example food chain: phytoplankton (green algae) – zooplankton (water flea) – zooplankton eater (young fish) – a larger fish species (perch) – top predator (human or sea eagle).

b. 85% of the phosphorus is located in the bones. The extracellular matrix of osteocytes includes hydroxyapatite (a compound of calcium and phosphorus). The human cell membranes consist of phospholipids and the DNA molecules (chromosomes) also contain phosphorus.

c. If you live in an area with a sewer network, very little phosphorus is able to end up in the sea, as up to 99% of it is removed in a wastewater treatment plant. However, sparsely populated areas still produce a lot of phosphorus emissions. Real estate located in groundwater areas or less than 100 metres from the shore must be equipped with a wastewater treatment system (since 1 November 2019).


Get to know the Finna classroom section on people and the sea (Ihminen ja meri)

https://www.finna.fi/Content/meri-ihminen

The material contains a number of photos about fishing. Pick a favourite photo and give your reasons for picking it.

Source: Finna, Espoo City Museum

https://www.finna.fi/Content/meri-ihminen


Model answer:

Student’s own answer. Pay particular attention to the pupil’s/student’s reasons for selecting the photo in question. The aim of the assignment is to get pupils/students to study historical photos about fishing as a livelihood.


The economic structure means the division of economic activity and jobs into three sectors: 1. primary production 2. industry and 3. services.

a. Find out how the Finnish economic structure has changed between 1860 and the present day?

b. In which sector does fishing belong?

c. How many professional fishers are there currently in Finland?

d. Why has the number gone down?


Model answer:

a. Primary production’s proportionate share of the GDP has continuously gone down and the share of services has gone up. The growth of processing accelerated after the Second World War, and the payment of war reparations sped up industrialisation. Finland has become a service society. It is worth noting that the GDP has increased greatly during this period.

b. Fishing is included in primary production.

c. According to Natural Resources Institute Finland (Luke), the number of active fishers in sea areas has more than halved from over 2,100 in the early 2000s. According to the Finnish Fishermen’s Association (SAKL), there are about 410 Group I commercial fishers in the sea areas and about 290 in the internal waters (as of 1/2018).

d. The burden of the job, smaller fishing quotas, reduced export to Russia due to economic sanctions (1/3 of Baltic herring and European sprat catch has gone to Russia), bureaucracy, increased numbers of seals and cormorants, etc.


1. Which of the following statements is incorrect?

a. Omega-3 fatty acids are necessary to the body. The human body cannot make them on its own and must get them from food.

b. There are three types of Omega-3 fatty acids (ALA, EPA, DHA), of which EPA and DHA are most prevalent in Finnish mushrooms.

c. Omega fatty acids are soft, unsaturated fats that always have one or more double bonds. Hard, saturated trans fats have no double bonds, which is why they have no omega number.


2. Which of the following statements is correct?

You get Omega-3 fatty acids mainly from:

a. fish b. meat c. vegetables

3. Which of the following statements is correct?

Omega-3 fatty acids have a particular impact on:

a. gastro-intestinal function and well-being

b. the function and well-being of mucous membranes and the brain

c. the well-being of hair, nails and skin


Model answer:

1. b. incorrect, we get most Omega-3 fatty acids from fatty fish, such as salmon

2. a. correct

3. b. correct


1. What is the chemical symbol and atomic number of phosphorus?

2. Which group and period of the periodic table is phosphorus in?

3. Present the electron configuration of phosphorus according to the quantum mechanical atomic model.

4. How does phosphorus reach the octet structure? What is the electron configuration according to the quantum mechanical atomic model in this case? Which noble gas has a corresponding electron configuration?


Model answer:

1. The chemical symbol of phosphorus is P and its atomic number is 𝒄 = 15

2. Phosphorus belongs to group 15 (pnictogens) and period three.

3. 1𝒄22𝒄22𝒄63𝒄23𝒄3

4. Phosphorus reaches the octet, i.e. eight electrons in its valence shell, by receiving three electrons (reduction).

The chemical equation that describes reduction:𝒄 + 3 𝒄− → 𝒄3−

The electron configuration of the phosphide ion is 1𝒄22𝒄22𝒄63𝒄23𝒄6, which corresponds to the outer electron structure of the noble gas argon.


5. In agriculture, gypsum is spread onto fields to reduce the phosphorus load that ends up in the Baltic Sea (read more: ymparisto.fi).

a. Give the formula of gypsum.

b. What chemical bonds are present in gypsum?

6. Phosphorus is soluble in water as phosphate ion. The phosphate ion in wastewater can be removed through a precipitation reaction in which e.g. iron(III) sulfate is added to the wastewater. Phosphorus is precipitated as low soluble iron(III) phosphate.

a. Give the chemical equation that describes precipitation.

b. What is meant by low-solubility substances?

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Assignment ideas to support phenomenon-based · a. Omega-3 fatty acids are necessary to the body. The human body cannot make them on its own and must get them from food. b. There