The problem

In Nepal many farmers living on the mountainside grow fruit and vegetables, including tomatoes. To earn a living they need to sell these at the local market. The problem is getting to market involves a long, dangerous walk down the mountainside and across a river, and tomatoes need to be transported carefully because they can easily get squashed.

The challenge

To design and build a model that can move tomatoes without squashing them. Here are some things to think about:

• You can only use the materials provided by your teacher.
• Instead of moving full-size fruit and vegetables down a Nepalese mountain, we want you to transport cherry tomatoes from a height set by your teacher to the floor. Your teacher might also give you a rope or string to work with.
• If your tomatoes fall to the floor by themselves, don’t count them. If they fell down a Nepalese mountainside, they’d be very, very squashed! Depending on the tomatoes your teacher chooses, and the height you’re working from, they might squash for you too. 
• Your solution can be as simple or as complicated as you like, but remember – think first, draw your ideas, check your materials, choose one design and make it.
• The bigger your container is the more tomatoes you will be able to carry. But, the heavier something is the greater the force of the impact when they hit the ground, so there is more chance the tomatoes will get squashed.

Didactic goals

The challenge is a fun hands-on and brains-on challenge suitable for KS2–5 students based on a real transportation problem facing farmers living on the mountains of Nepal.The challenge is flexible and can help you deliver:

• Enrichment activities – for STEM and National
• Science and Engineering Week
• CREST Discovery Award
• Science curriculum on forces, friction and levers at Key Stages 2-4 Cross curricular opportunities

The challenge ground rules

• The tomatoes need to be transported a minimum of one metre along the ground starting from desk height. However, the challenge is more spectacular, and you are more likely to get squashed tomatoes if you set a height of more than two metres, and a horizontal distance of 1.5 - 2 metres. (This can be done by starting the run from the top of a metre rule standing vertically on top of a chair, desk, stool or lab bench, taking care to ensure it’s safely set up and supervised.)
• The tomatoes cannot be touched whilst they are moving, catapulted or ‘flown’ in any way. They must be moved in a controlled way so they don’t just crash into the ground and get squashed.  
• You can also adapt the challenge by asking groups to either aim for the greatest weight of tomatoes transported in one trip, or go for speed of operation and ask them to aim for the greatest weight moved in two minutes. In both cases, the group that transports the heaviest weight of tomatoes wins.

Equipment and materials

Students will need a range of appropriate modeling material and equipment for the challenge. They include:

• Things to make a framework or basket from (e.g. K’Nex, Lego, Meccano, margarine tubs)
• A means to attach their basket/ framework to the mode of transport and pulleys, ramps or similar to allow everything to move
• Ways to stick everything together (e.g.string, tape)
• String

About Practical Action

Fritz Schumacher (no relation to Michael!) was a man who believed that simple technology could change people’s lives for the better. To prove his ideas could work and help some of the World’s poorest people he started the charity Practical Action in 1966. Since then Plan Action has been working in countries like Nepal, Sudan, Bangladesh, Peru and Zimbabwe, improving the lives of local people using Schumacher’s vision that the right idea – however small – can change lives for the better.