Session 2 - Shortest Route

Objectives

• Part 1: Create a more complex algorithm to deliver one or more packages on the way.

• Part 2: Understand and use simple repetition

Resources

• Levels 17 and 18 in Rapid Router

• Computers with internet access

• Projector or Interactive Whiteboard (IWB)

• Printed sheets for level 17 maps (1 per pair) Printed vans with L and R

Vocabulary

• directly

• on the way

• destination

• loop

• repetition

Lesson guide

Warm-up (15 mins)

• Pupils continue up to level 15 for up to 10 minutes

• Show level 16 https://www.codeforlife.education/rapidrouter/16/ and discuss how the delivery driver would decide which house to deliver to first.

Unplugged Activity (15 mins)

1. Look at level 17 together on the IWB and give the children the printed sheets to match.

2. Assess children’s learning by asking them to predict the code needed for this level without using the computers

3. They should also count the number of blocks used

4. Ask pupils to try their predicted routes on the Rapid Router program and indicate if they had the predicted route correct.

5. Pupils should record if their algorithm was correct and what their score was

6. Discuss any less-optimal solutions and encourage the class to improve on them

Paired activity (5 mins)

• Pupils complete level 18 in pairs

• Discuss less-optimal solutions and encourage class to improve on them

Introducing Loops (15 mins)

1. Show video to introduce repetition https://youtu.be/vFGd0v3msRE - this video is also on the introduction to level 19

2. Show level 19 and ask pupils what instruction is repeated; it is the move forwards block

3. Collaboratively develop a solution to level 19 and introduce the repeat loop

4. Demonstrate usage in Rapid Router

Paired Activity (15 mins)

1. Pupils complete levels 19 – 21 in pairs; allow some to continue to level 22

Hint: If pupils are struggling to use loops in these levels, encourage them to solve the level without loops and then look for a pattern to repeat. They will get a low algorithm score if they don't use a loop. E.g. on level 21, the pupils should find that move-forwards, left, right, left is repeated.

Encourage pupils to review their answers if they don't score 10/10 for both the route and algorithm score.

Share and Review (5 mins)

• Explain that next time you are going to look at more complex loops.

• What did pupils find difficult?

• How did they solve their problems?

• Recap on the keywords.