Teacher’s Notes: Cooking Bolognese
Resources needed for this lesson: Pen and paper, student hand-out (attached)
Lesson length: Approximately 1 hour
Aimed at: GCSE/AS Level Students
Slides 2 to 5: “Task”, “Useful Information”, “Your Tasks” and “Precedence Table”
(approximately 10 minutes)
Introduce the task given and make sure the students understand what they are being asked
to do. Briefly go over the “useful information”: not too much detail is needed here however
as this slide is included on the student hand-out (which will be distributed later).
Tell the students that they have found a recipe online which outlines the different tasks they
need to complete (please see slide 4) and how long it will approximately take them to
complete each activity.
Ask the students to use this and, in groups or pairs, think about which tasks can only occur
after other tasks have been completed. The students should display their workings out in a
table, considering each new activity in turn. Draw this table on the board so that students
understand how they should display their ideas:
Activity
A - Boil water
B - Add pasta to water and cook
C - Chop up onion, carrot and bacon
D - Cook minced/quorn meat
E - Add onion, carrot, bacon and
tomato puree to minced/quorn meat
and stir
F - Drain pasta
G - Mix Bolognese and pasta
together and serve
State that this is called a precedence table.
Depends on
Ask students to then compare their table to the correct table shown on slide 5: “precedence
table”.
Slide 6: “Activity Network”
(approximately 5-10 minutes)
Explain that an activity network is a visual way of displaying the information given in the
precedence table.
Use the diagram on slide 6, showing the activity network, to explain what each part of the
activity network means.



Earliest start time
This is the earliest possible time the activity can start, without delaying the overall
minimum project time possible.
Latest finish time
This is the latest possible finish time for the activity to be completed by, without
delaying the overall minimum project time.
Dummy activity
This is an activity which has zero duration. Its purpose is to show that activity E must
only occur once activities C and D have been completed.
Explain that the purpose of creating an activity network is to be able to calculate the earliest
start times and latest finish times of each activity, in order to find out what the critical time
of the project is. The critical time of the project is the quickest time the project can be
completed in, taking into consideration the constraints of any activities which depend on
others having been completed beforehand.
Slide 7: “Critical Path Analysis”
(approximately 5-10 minutes)
Tell the students that this whole procedure is called critical path analysis. Its purpose is to
allow one to understand all of the activities which need to be completed for a specific
project and organise when exactly they need to be completed by. Inform students that it
relates to the discipline of Operational Research. Operational Research involves applying
often advanced and analytical methods to real life problems, in order to help make better
decisions.
Ask the students if they can think of any examples where this may be used in real life and
why this algorithm would be useful. (E.g. building a house – critical path analysis is useful
here so that the project manager can ensure that materials for specific tasks are ready on
time/staff are available etc.)
Show students the examples on the board. Briefly discuss the case study on Network Rail, by
clicking the link to navigate you to the appropriate webpage.
Slides 8 and 9: “Working Out the Earliest Start Time (EST)” and “Working Out the Latest
Finish Time”
(approximately 5-10 minutes)
For these slides, explain to students how they calculate the Earliest Start Time and Latest
Finish Time, using the information given on the slides. This slide is very important because
students will need to do these calculations themselves later on in the lesson therefore feel
free to take some time emphasising each point on the slides.
Slides 10 to 19: “Who Wants to be a Millionaire?”
(approximately 5-10 minutes)
This is a short quiz in the style of “who wants to be a millionaire?” to test students about
what they have just learnt about the calculations needed to work out the earliest start times
and latest finish times of activities in a network. The navigation is already correctly in place,
so when students choose an answer, click on the appropriate answer on the slide and it will
lead you to either a congratulatory slide or a “sorry your answer is incorrect” slide. Once the
quiz is finished (i.e. the students reach the final congratulatory slide saying they have won
£1,000,000 or they have reached the “sorry your answer is incorrect slide”), go straight to
slide 20.
Encourage large student participation for this activity: they should discuss their answers in
pairs or groups of 3.
Slide 20 (and 21): “Your Turn!”
(approximately 10-15 minutes)
Distribute the student hand-out. This gives all of the information from the slides about the
task and how to calculate the Earliest Start Times and Latest Finish Times of each activity.
The second section is then a copy of the activity network for cooking spaghetti bolognese.
Encourage students to calculate the earliest start times and latest finish times of each
activity, in order to complete the activity network.
(Please see slide 21 for a copy of what the completed activity network should look like.)
Once students have found the critical time of the project (35 minutes), they should add this
time plus the 1 hour it takes for one to eat the spaghetti bolognese and wash up afterwards
to 7pm to get 8.35pm. Using this, they should then be able to conclude that, after adding on
a further 15 minutes to include the walk to the cinema, the film showing that one should go
and see is at 9.00pm (due to one arriving at the cinema at 8.50pm).
If time at the end, ask students why this plan may not be completely accurate, i.e. what are
the disadvantages with the plan in terms of coming up with a definite solution. (Answers
could include: some activities may take longer than expected as the lengths are only
approximate, external factors such as one getting distracted by a flatmate returning home,
one may not have all of the necessary ingredients/equipment to complete a specific task.)
Slide 22: “Evaluation”
(approximately 10 minutes: 5 minutes evaluating and 5 minutes discussion)
Ask students to work independently to answer the questions given on the slide. This task is
intended to prompt students to reflect on what they have learnt during the task, as well as
help them to consolidate the material covered.
Conclude by discussing with the students the answers they have come up with.