Useful parts of plants: coffee, cacao, lentils

Activity overview

Run the activity

This activity has been co-created with the Eden Project as part of Explorify’s collaboration with Science and Discovery Centres.

1. Show the three images above and ask everyone to come up with as many similarities and differences as they can. If they get stuck, prompt them to think about:
•    appearance
•    what they do
•    where they might be found

2. Then, everyone needs to decide which one is the odd one out and why. Encourage a reason for every answer and there is no wrong answer!

Background science

Fruits develop from flowers and contain seeds. That’s true for coffee, cacao and lentils. Lentils are a type of legume, like garden peas, which tend to be grouped with vegetables. To a botanist, however, they’re fruit.

Coffee is the name of a drink made from the seeds of a tropical, evergreen plant called Coffea, that grows in warm climates. Although there are more than 100 species, almost all coffee comes from just two of these: Arabica and Robusta. The seeds are separated from the fruit, then roasted. We know them as ‘coffee beans’. The sweet flesh of the fruit – the ‘coffee cherries’ – is often discarded, though it can be made into a drink, or used as a fertilizer or animal feed. Each cherry usually contains two seeds. Almost 150,000 tonnes of green (not yet roasted) coffee beans were imported into the UK in 2021, and 98 million cups of coffee drunk each day. Instant coffee (invented in New Zealand in 1890) is made from concentrated, dried coffee extract. It remains popular, not least because the dried grains are soluble so coffee can speedily be made from it.

Cacao are tropical, evergreen trees on which grow the large pods (up to 20cm in length) that are the fruit of the tree. From these, chocolate is produced. The pods ripen at different times across the year, rather than all at once. Often yellow when ripe, they appear in a range of colours and, unlike most fruit, grow directly from the trunk of the tree, or from a large branch. The pods are similar in shape to lemons but with grooves and ridges running from pointed end to stem. Beneath the thick rind, 30-50 seeds, known as cocoa beans, are contained in a sweet, slimy pulp. These beans are fermented, roasted, and ground before being mixed with other ingredients, including sugar and cocoa butter (the fat of the bean), to make different chocolate products.  

Fruit growing directly from the trunk of a cacao tree (image credit: PSTT for Explorify)

Lentils are the nutritious, edible seeds of a plant that’s been cultivated throughout human history. The name derives from the curved shape of the seed, which resembles a lens. Related to beans (legumes), lentils are low-growing plants (up to 50cm) that produce small (1.5cm long), oblong pods each containing a couple of seeds. The seeds can be red, brown, green, or yellow. Puy lentils are a special type of lentil grown on volcanic soil in France. More than half the world’s lentils are grown in Canada. In Middle Eastern and Indian diets, lentils are a staple food, often cooked as dahl and served with rice, chapati or naan bread.

Watch out for... 

Not all fruit is edible. Holly and ivy berries, for example, are poisonous to humans.

Plants have many more uses than simply nourishing us with food. Children may also not be clear about the variety of plants and plant parts we eat. As well as the fruit, we eat the stems, flowers, roots, seeds, and leaves of particular plants. 

This does not need to be corrected during the session, but you can pick it up later.

Take it further

Activities

To help children make the link between the pictures of the plant growing in its natural habitat and the products they become, it is a good idea to show the children some of the products – ideally the actual items, but if this isn’t possible, using pictures.
 
For this activity, you could, for example, find: 

• CACAO a chocolate bar or some cocoa powder.
• COFFEE instant coffee granules or coffee beans.
• LENTILS a handful of lentils or a tin of soup.

Pass around the objects made from the three plants. Encourage the children to use their senses as they handle them. Then discuss where they have encountered the objects before. Show the images of the three plants and explain that each object is made from one of them. Can they suggest which one is which and offer a reason why?

Kew has produced three lessons that teach children why plants matter in our daily lives for food, shelter, medicine and wellbeing along with instructions on how to create a plant museum. 
     
In this film from the Royal Society, Brian Cox is shown how children can safely investigate melting chocolate. The accompanying notes can be found here.

Sprouting lentils in dampened cotton wool is easy to do as this film shows and a good way to learn about germination and growth.
 
If you are in the area, consider visiting Eden for an educational experience that will connect your pupils with nature in an immersive and unforgettable way. 
 
Or you could take an exciting virtual tour of the Eden Project here. 

Linked Explorify activities - our recommendations:

• Odd One Out Useful parts of plants: bamboo, cinnamon, rubber tree  Which of these plants do we eat, or do they have other uses? Ideal preparation for a visit to the Eden Project.
• Odd One Out Useful parts of plants: rattan, sugar cane, vanilla Which of these plants do we eat, or do they have other uses? Ideal preparation for a visit to the Eden Project.
• What’s Going On? Fantastic fibres This film shows paper being made in two different ways, from papyrus and from wood pulp.
• Zoom In, Zoom Out Bumpy eyes A close-up look at a pineapple; a plant you can find growing at Eden.
• Zoom In, Zoom Out Blackened edges Another plant you can find growing at Eden, the banana.
• Zoom In, Zoom Out Orange and waxy Learn about the Prickly Pear, a cactus grown for its vitamin C rich fruit.
• What If? What If all plants were the same? Consider the value and huge variety of plants.

Watch

Children explore a coffee farm in Hawaii and learn how it’s processed in this ten-minute film.  Alternatively, just watch from 1 min 30 in to 2 min 30 to give children an idea of what coffee cherries and a bush look like, as well as where the word ‘coffee’ comes from.   

Find further information and a film about cacao on the Eden Project site here.  

This short film from Kew shows what’s inside a cacao pod.

This film explains about Fair Trade in the context of cacao growing.

This film from Chester Zoo explains how replacing forests with crops to make money - deforestation – causes a problem for the animals that were living there.

Cross-curricular

In Geography, mark on a world map where these plants grow.