Session 3 - Complex Routes

Objectives

• Learn how to build up solutions to complex loop problems by writing out longhand and then searching for patterns to repeat

Resources

Resources

• Levels 23 to 25 in Rapid Router

• Printed sheets for level 24 maps (1 per pair)

• Long solution for level 24 - display

• Resource sheet

Lesson guide

Introduction (10 mins)

1. Show level 23 and ask pupils what they notice. You are looking for pupils to notice the pattern. Ask them to think back to last session and what might help them here (loops).

2. Indicate the repeat block and make sure the pupils realise that they can change the number inside to change the number of times the code repeats.

3. Ask pupils how they can use the patterns in this route with loops.

4. If pupils are unsure, allow a long solution without loops; then look for a pattern that repeats

5. E.g. for the first half of the route*: * The blocks must be joined together and connected to the Start block to run. This is just for illustration.
6. If pupils suggest a less optimal solution than the one below, try it and lead them to a shorter solution through questioning and looking for a bigger pattern

Extension: Can they complete the level using three loops only? See the solution below:

Unplugged Activity (15 mins)

1. Look at level 24 together on the IWB

2. First, ask the pupils to tell you the solution without using repeat

3. Then hand out a printed copy of this solution and a printed sheet for the level and ask pupils to shorten that code using loops

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

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

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

Paired Activity (15 mins)

• Pupils complete levels 24 - 25 in pairs

• More confident pupils can move ahead to level 28, allowing others to master levels 24 and 25

Unplugged activity - extension

Give gifted and talented children a resource sheet on nested repeat, with this code, and ask them to draw the route. The solution is shown here:

Share and Review (10 mins)

1. Explain that next time you are going to look at Loops with conditions.

2. What did pupils find difficult?

3. How did they solve their problems?