Planning scientific tests to solve a bakery problem | 14-16 years

In this activity, students are set a problem by the manager of an imaginary bakery. The bakery explains it is looking for two people to do some occasional laboratory work for it. To decide who to employ, the bakery manager asks the school to set up an analytical exercise for students to show what they can do. In the trial, groups compete with one another to tackle the problem set by the bakery manager.

Learning objectives

Students will understand that:

• Tackling a problem requires planning.
• Observations and measurements must be recorded.
• Results must be interpreted.

Sequence of activities

Introduction

1. Outline the purpose of the session before arranging the class into pairs.
2. Give each student a copy of ’What the bakery manager needs’. Show samples of the ingredients used to make the cake.
3. Ask students to highlight on the recipe which ingredients are white solids.

The bakery problem

1. Hand out a copy of ‘The bakery problem’ to each student. Give them a few minutes to read and discuss in their pairs.
2. Discuss with students and make sure they understand what they need to do and what criteria will be used to judge their suggested solutions. Use ‘thumbs up’, ’thumbs down’ or ’thumbs horizontal’ to check they know what to do.

Planning tests

1. Give pairs up to 10 minutes to suggest possible tests. Ask students to hold up a green card when they are ready to have their ideas checked.
2. Visit each pair when they are ready and respond to their ideas with prompt questions and suggestions. Remind them that:
   • Scientists often modify their ideas once they begin to try things out, and this may well happen once they get started.
   • If they do want to change something it must be checked with the teacher.
3. Once a pair’s tests have been decided, tell them that they will need to share the work to get the practical work done in time – how is up to them.

Carrying out the practical work

1. Supervise the students while they carry out practical work to check that their ideas work.
2. Give each student a copy of the ‘Results table’. Explain what should be written in each column.

Results and report

After the practical work, ask the pairs to:

1. Review their results.
2. Write a report for the bakery manager.
3. Hand in the report (to be returned later with constructive comments).

Choose the winning group and explain to the class the reasons for that pair being chosen.

Plenary

Organise a plenary and ask one member of each pair to describe what went well, what went less well and what they found out about tackling this kind of problem.

Commentary

The bakery problem is in itself an assessment. Students have to come up with a resolution to the problem that would be a test for their suitability as an employee. This is a potent stimulus, if the introduction to the activity is sufficiently anchored to real life.

The use of questions and constructive feedback, by the teacher, and the informal assessment, as students collaborate to solve the problem, also contribute as stimuli to learning.

Practical notes

Apparatus

For each pair of students:

• Eye protection
• Tripod
• Test tubes, including Pyrex ones
• Ignition tubes
• Bunsen burner
• Gauze
• Heatproof mat
• Test tube holder
• Test tube rack
• Balance
• Clamp stand
• Beakers
• Glass droppers
• Glass stirring rod
• Spatula
• Litmus
• Microscope, slides and cover slips
• Power pack, with leads and bulb
• Electrolysis cell (as a distracter)

Chemicals

• Dilute hydrochloric acid
• Distilled water
• Universal indicator solution
• Limewater
• Samples of the following substances:
  • Sugar (sucrose)
  • Baking soda (sodium hydrogencarbonate, by mixing flour and citric acid)
  • Salt (sodium chloride)
  • Plain white flour
  • Citric acid
  • Baking powder

Other equipment

• Green cards, one for each student

Health, safety and technical notes

• Read our standard health and safety guidance.
• Wear eye protection.
• It is the responsibility of the teacher to carry out an appropriate risk assessment.