Mini Minds Hub · Free printable
Drone Delivery Dash: Free Printable Worksheet for Year 9
- ForYear 9
- StageKey Stage 3
- CostFree
- FormatPrintable PDF
Drone Delivery Dash is a free printable computing worksheet for Year 9 (ages 13 to 14), in Key Stage 3. Pupils help a drone carry medicine from Hub to Clinic using the least battery. They trace a greedy route, fill in a shortest path table and then judge which route is better. Page 2 gives the grown up notes, help ideas, a stretch task and the answers.
It comes from the Mini Minds Hub, the free library of printables from Jaques of London, the British games and toy company that has been making games for families since 1795. Print both pages, give page 1 to the pupil and keep page 2 for yourself. Black and white printing works well.
What is on the sheet
Pupils look at a map of islands joined by paths, where each path costs some battery. They trace a greedy route first, then complete a table that records the cheapest cost from Hub to each island and which island it arrived from. The sheet mixes multiple choice questions with three answers each, the table, and numbered questions with space to explain their thinking.
- Island
- Cheapest cost from Hub
- Arrived from
- What is the cheapest total cost from Hub to Clinic?
- Why did the greedy route go wrong?
- How much battery does the best route save over the greedy route?
Worked example: a different network
A drone must fly from Depot to Shop. Paths and costs: Depot to P is 4. Depot to Q is 9. P to Q is 3. P to R is 11. Q to R is 5. R to Shop is 6. Find the cheapest cost to Shop.
This network uses different islands and costs from the sheet. It shows how to build the table outwards, always settling the cheapest island first.
Method 1: build the table outwards- Depot costs 0. Look at its paths: P is 4 and Q is 9 so far.
- The cheapest unsettled island is P at 4, arrived from Depot. Update from P: Q via P is 4 + 3 = 7, which beats 9. R via P is 4 + 11 = 15.
- The cheapest unsettled island is now Q at 7, arrived from P. Update from Q: R via Q is 7 + 5 = 12, which beats 15.
- Settle R at 12, arrived from Q. Then Shop is 12 + 6 = 18, arrived from R.
- Start at Shop. The Arrived from column says R.
- R arrived from Q, Q arrived from P and P arrived from Depot.
- Read the route forwards: Depot, P, Q, R, Shop. Add the costs: 4 + 3 + 5 + 6 = 18.
Why plan routes like a computer scientist?
In computer science, a set of points joined by links is called a network, or a graph. Each link can have a cost, such as distance, time or energy. Finding the cheapest way through a network is a classic problem. Route finding software, delivery planning and computer networks all use ideas like it.
A greedy method makes the best looking choice at each step and never looks back. Sometimes that gives the best overall result and sometimes it does not. A shortest path table is more careful. It records the best known cost to each place and updates it when a better route appears. Comparing the two methods shows why checking a plan matters.
Quick facts about route planning
- A drone carries a limited battery, so planners care about how much energy each route uses.
- A greedy algorithm picks the best looking option at each step.
- Dijkstra's algorithm is a famous shortest path method. It is named after the Dutch computer scientist Edsger Dijkstra.
- In a network, the points are often called nodes and the links are called edges.
- The cheapest route is not always the one with the fewest steps.
Skills and curriculum link
- Tracing routes
- Using an algorithm table
- Evaluating greedy choices
- Comparing methods
- Explaining reasoning
Ideas that help with this sheet
- Cost adds upThe cost of a route is the sum of every path along it. Add as you go and write each running total down.
- Work outwardsStart at Hub and settle the cheapest unsettled island first. Then use it to update its neighbours.
- Keep a recordThe Arrived from column lets you trace a route backwards from any island to Hub.
- Test the planA method that feels sensible is not always best. Compare its total with another route before you trust it.
Key words
- AlgorithmA set of clear steps for solving a problem.
- GreedyChoosing the best looking option at each step without planning ahead.
- Shortest pathThe route between two places with the lowest total cost.
- NetworkPoints joined together by links.
- CostWhat a path uses up. Here it is battery.
- TraceFollow a method step by step and write down what happens.
How to use it
- Print both pages. Page 1 is for the pupil. Keep page 2, which has the notes and answers.
- Read the task together. Make sure the pupil knows the aim is to use the least battery from Hub to Clinic.
- Pupils do the greedy trace first, then complete the table by working outwards from Hub, island by island.
- Check against page 2. Ask, "How did you decide which island to settle next?" The reasoning matters as much as the answer.
- Come back another day and redo any part that felt tricky. Repeating a familiar sheet builds confidence.
Help, stretch and game ideas
If it feels too hard
Sketch the islands and paths on scrap paper before tracing routes. Write each cost on its path. Fill in the table one island at a time, and for each island check every path that leads into it, not just the first one you see.
To stretch confident children
Invent a new path that makes the greedy route the cheapest. Explain your reasoning. Then design a network where greedy and shortest path give different routes, and write a short note explaining why the two methods disagree.
Make it a game
Pairs design a network of islands with costs, then swap papers. Each player races to find the cheapest route and fill in a table. Compare totals and routes. A point goes to whoever is correct, and a bonus point for a clear explanation.
Mistakes to watch for
Watch forA pupil takes the cheapest path out of each island and assumes that gives the cheapest route overall.
Try thisAdd up the full route cost and compare it with at least one other route. Ask what the greedy choice could not see.
Watch forA pupil fills in the table by finishing the islands joined directly to Hub first, even if those paths are expensive.
Try thisSettle the island with the lowest total cost so far, then update its neighbours. Check every route into each island, including ones that go through another island.
Watch forA pupil writes the cost of the last path instead of the total cost from Hub.
Try thisSay "from Hub" aloud each time. Add the cost of the new path to the total of the island you arrived from.
Talk about it
- Why might the cheapest next step not lead to the cheapest journey?
- How did you decide which island to fill in next?
- What does the Arrived from column let you do?
- Where in real life could you plan a route to save energy or time?
- Could two different routes have the same cost? What would you choose then?
- How could you check your table is right?
Take it off the page
Map a journey
Draw a map of places you visit, such as home, school and a shop. Add a cost to each path, such as minutes walked. Find the cheapest way between two places.
Greedy or planned
Plan a tidy up of your room two ways. First do whatever looks quickest each time, then plan the whole job first. Talk about which worked better.
Human network
Use string and sticky notes to make a network on the floor. Give each string a cost and let a friend find the cheapest route.
Who it is for
Parents
Sit with your pupil for the first trace, then let them lead. Ask them to explain each choice aloud. You do not need to know the method, as the notes and answers on page 2 will guide you.
Teachers
Use it as a starter, plenary, early finisher task, homework or table activity after teaching algorithms. It needs no preparation beyond printing. The help and stretch ideas on page 2 suit mixed ability groups.
Home educators
Print it as part of a wider computing plan. It pairs well with programming, puzzles and everyday talk about planning routes. Use it again for revision or with brothers and sisters.
Where this fits in computing
Before this sheet, pupils should be comfortable following and writing algorithms, reading tables and adding numbers accurately. Tracing a method step by step and recording what happens are the key habits.
After it, pupils can compare other algorithms, such as ways of searching and sorting. They can test whether a method always works and think about efficiency. Later study meets formal shortest path methods and more complex networks.
Questions parents and teachers ask
- What age is Drone Delivery Dash for?
It is written for Year 9 (ages 13 to 14), in Key Stage 3. It suits pupils who can follow an algorithm and want to compare methods. Younger pupils can try it with support.
- What will pupils practise?
They practise tracing routes, using an algorithm table and evaluating greedy choices. They compare a greedy route with a shortest path table and explain which is better.
- Does the sheet include answers?
Yes. Page 2 is for the grown up and includes the answers, notes on how to use the sheet, help for pupils who find it hard and a stretch idea.
- What if it feels too hard?
Let pupils sketch the islands and paths on scrap paper before tracing routes. Fill in the table one island at a time, starting from Hub and settling the cheapest island first.
- Is it free?
Yes. It is free to print for home and classroom use. You can print it again for brothers, sisters or revision.
- Is it a screen free activity?
Yes. It needs only paper and a pencil, so it works well for quiet time, rainy days and school holidays. It still practises real computing thinking.
- Can teachers use it in class?
Yes. Teachers can use it as a starter, plenary, early finisher task, homework or table activity. It needs no preparation beyond printing, and black and white printing works well.
Preview the full PDF
Made by Jaques of London, making games for families since 1795. A printable supports classroom learning and does not replace a teacher.