Project Scheduling Exercise "Cup of Tea"

I've been asked a number of times to do a bit of adhoc training on use of Project scheduling tools such as Microsoft Project. In this post I have given some background to modern scheduling tools and have posed a simple exercise which can be attempted by learners and experts alike. The workings for (my version of) the answers are made in a separate Post.

Some useful history for younger folk!

Critical Path Analysis alongside Project Evaluation and Review Technique were developed in the 1950s as techniques to help model Projects, have a read about them if interested. My first degree was in Civil Engineering and at University I learnt these techniques the hard way, by hand calculation! 

Now software tools do all the hard work but in some you can break the golden rules of the technique so I like to keep things simple and in line with what I learnt was needed to produce a valid network:

• a Start and End milestone for the Project
• all tasks in between these two points have predecessor and successor tasks 

Software tools often allow Work Breakdown Structures (WBS) to be documented in the schedule but encourage bad habits like dependencies linked to summary tasks.

(Read down later for definitions)

The Project - Making a Cup of Tea

What better example Project for an Englishman than to make a cup of tea. The Project work area is the worktop around a electric kettle in a kitchen. All non human Project resources are available in the kitchen and to start with let us make the Project Manager (David) do all the real work for a change :-) 

I have listed the Project tasks, durations, effort and task predecessors as follows. I don't mind you criticising my scheduling skills but please don't criticise my approach to make a good cup of tea except that I should really be using a teapot! 

However when scheduling the Project I am going to use Minutes rather than Seconds for Duration and Effort to make the schedule more visible in most tools.

Other Project information is:

• Start date is 1 January 2015 at time 10:00
• There are no periods of non working to account for
• Remember to enter task duration & effort in minutes not seconds
• All tasks are carried out by one resource named David (to start with)

So please get scheduling and answer the questions below

Questions about Cup of Tea Project Schedule

Your questions are as follows:

1. What task numbers are on the critical path for the basic network?
2. If there is no consideration of over allocated resources, what is the earliest finish time of your Project?
3. If you remove the overallocation of tasks to David, what is the earliest finish time of your Project?
4. If you bring in as many team-mates as you like to help David, reallocating some of the tasks to these folk (but nobody is over-allocated work), what is the earliest finish time of your Project now and how many people did you require? 

Definitions and other Help

Here are some definitions and general help for you:

• Task - a specific item of work
• Milestone - an event; it has no duration or effort. Typically used to denote a significant event such as the completion of a phase of the project or of a set of tasks
• Duration - the elapsed time to complete a task
• Effort - the amount of actual work required (in time units) for a particular task. A good illustration in the example "Cup of Tea" plan is the task "Boil Kettle". The effort required is minimal (basically to throw the switch) but the duration is governed by the amount of water, the temperature of the water poured into kettle and the capacity of the heating element
• Task Predecessor - A task that must be started or finished before another task or milestone can be performed
• Over-allocated Resource - a resource has been allocated more work in the plan than can be achieved in the available time 
• Resource Levelling - process to remove the over-allocation (and ideally under-allocation) of resources and as far as possible avoid peaks and troughs in the resource schedule. Some tools allow this to be done at a click of a button but I have never had much success with this and prefer to do by hand guided by specific views setup. In a real-world project I will allow some over allocated resources (within reason) because estimates may not be correct and overtime can be used
• Work Breakdown Structure - decomposition of high level project deliverables into tasks and sub-tasks
• Critical Path - typically the path through the schedule of tasks which determines the shortest duration for the project. If any task on the critical path is delayed this will delay the completion of the project.

Answers

The answers for the questions posed above are:

1. 1,14 (start and end milestones) and in terms of real tasks, 4, 6, 7, 8, 11, 12 
2. 14:30
3. 14:50
4. 14:30 with one extra person

The workings for these answers can be seen here.