Best Practice

Extended science practical investigations

Teaching resources STEM Skills Post-16
Extended practical investigations take time and planning to get right, but the results in terms of staff and student motivation can make this worthwhile. They can also inspire students to continue with their STEM studies into higher education. Head of chemistry Lisa Niven explains

I grew up in the American education system, attending a small high school in rural Minnesota. My timetable was very different than what I have experienced as a teacher in England. I had science every morning for an hour – roughly 700 hours across my high school experience.

From all that time, the most prevalent memory I have is of our week-long investigation attempting to find the percentage of copper in a penny. I recall getting a result of 120 per cent copper content and having to reflect on why (turns out I didn’t let it dry properly before measuring its mass, a rookie error). Nearly 25 years later I believe that that practical experience heavily influenced my decision to study chemistry after high school.

I entered the teaching profession in 2004 via the Graduate Teaching Programme – a “trial by fire” entry to English education. I learned a lot very quickly, not least an appreciation that pupils need to feel a purpose to their learning, other than simply gaining a qualification. I learnt how to answer those common “when will I ever need this?” questions.

Science capital

The key is context. If I could hook pupils with a relatable context, they were more engaged and the learning seemed to stick with them longer.

Recent work by UCL and Kings College London about building students’ science capital supports this observation. For those unfamiliar with science capital, it is a way of describing one’s knowledge, attitude, skills and experiences of science. As teachers, we can influence a pupil’s science capital by making a few key tweaks to our lessons.

An easy way is by personalising and localising lessons – using pupils’ interests and their local area to ground issues for discussion. Consider the rather dull topic of hard water. Living in Yorkshire, we have a lot of hard water, so I introduced the topic by asking pupils to describe the inside of an old kettle – even showing pupils the one used by science staff.

I then challenge pupils to link those observations to “clogged” washing machines and later extend to ask why a dishwasher might indicate that “salt” needs to be added so it can work properly.

Most pupils use a kettle – thus personalising the discussion and initiating class discussion, the context also helps to tease out what pupils already know and provides a starting point from which to address misconceptions.

I might also ask who’s visited Mother Shipton’s Cave and the petrifying well in Knaresborough. This links to the second way of building science capital – eliciting and valuing pupils’ experiences of science outside of school and linking those experiences back to the curriculum.

Finally, we can tweak lessons to help pupils view science as providing skills for life outside of the classroom. For instance, consider the myriad of metals used to make wedding bands. Some may even wear jewellery in lessons – do any have marks left on their skin? Do they know of anyone who has experienced that? What do they think causes this?

By eliciting what they already know we can now link it to the curriculum. For instance, consider the different reactivities of the metals – pupils could justify choices of which metal to use for a wedding band.

Good Practical Science

An easy way to incorporate all three pillars of science capital is via extended practical investigations. The Gatsby Foundation’s Good Practical Science report (2017) defines an extended investigative project as one that lasts more than one week and which has no pre-determined outcome; by that, I mean no “correct” final answer to the investigation.

Let’s be clear, an extended investigative project is not a new idea. However, in today’s world of increased curriculum content, accountability stakes and shrinking budgets, it is easy for one to justify removing it from the curriculum or to discount its value-for-time when developing a new scheme of work.

As referenced in the Good Practical Science report, the Wellcome Trust’s Young Researchers report (Bennett et al, 2016) shows how extended investigations give pupils a sense of what “real science” is like, with all its frustrating pitfalls and exhilarating successes!

But these investigations have the added, hidden advantage of helping pupils develop the transferrable skills that both employers seek and which prepare pupils for life beyond the classroom – the ability to plan, problem-solve, communicate with others, and organise one’s self, etc.

However, the Gatsby report is concerned that only 15 per cent of schools offer pupils the opportunity to complete an open-ended investigative project.

Now I firmly believe that facilities do not need to be state of the art to sufficiently support extended projects. However, what is important, as the Gatsby report finds, is that unless these extended projects are specified as part of the curriculum, they are unlikely to become embedded.

Inquisitive pupils?

For my own experience, during the past 12 years across the schools I have worked in, I was noticing an increasing lack of inquisitiveness in pupils. Too often pupils were simply accepting what they were told, or the allotted time in which to complete the practical limited their opportunities to “play” with equipment or investigate follow-up questions.

Sometimes pupils simply gave up partway through an investigation because they felt they were not getting what they considered was the “right” result. Extending the time during which pupils can perform an investigation provides pupils the opportunity to develop their questioning, usually by trial and error. This last bit is especially important to me.

Extended projects allow pupils to come into the lab and make mistakes and realise that everyone around them is making mistakes as well. Nobody is penalised for making those mistakes because they are made with a safety net in place. Pupils can act on feedback and build resilience in the face of a challenge. More than anything else, my intended outcomes from the extended project were those transferrable skills. So, what exactly did we do and how did it work?


The Iron in Food project

My latest posting coincided with the government changes to A levels. Prior to my arrival, it had been decided that the incoming year 12s would start the AQA specification while the year 13s would finish on Salters. It was my first experience of the extended project element of the Salters course.

I was guided by our head technician and teaching colleague in its final delivery, while simultaneously awed by the variety of skills and increased confidence displayed throughout. More than anything, the project reminded me of that copper penny practical from my own school days.

But it all really began over lunch. A pregnant colleague was bemoaning her spinach salad, which she was eating as it was a good source of iron. This instigated a discussion about possible alternatives. A quick online search and we were surprised by the results: mushrooms, lentils, even chocolate!

Which option would be the best? How would you find out? I recalled a Salters redox titration involving spinach that I had trialled at a previous school with good results, and we discussed the possibility of testing spinach against sprouts or broccoli.

At the time, I was considering plans for the year 12 groups upon their return from study leave and exams. It was a perfect opportunity to trial an extended investigation.

We carefully considered the size of the year group and the group sizes. I particularly wanted different food groups and different varieties of each food group to be investigated so that each pupil had an individual investigation, but a common purpose.

We chose five food groups that pupils could investigate with sufficient variety for the number of pupils (green veg, mushrooms, lentils, fruit juice, and drinking chocolate). With the old Salters redox practical instructions as a guide and with the help of my chemistry colleagues, we trialled the different food groups, adapting the instructions as necessary (i.e. how much of each sample would be adequate to create a stock solution that would achieve reasonable results during titration).

Upon their return, the class of 2016 – my guinea pig group – got stuck in. I learned much in that first year, and the feedback from colleagues, pupils, and parents was very positive. Consequently, I have incorporated the Iron in Food project into our scheme of work, making it a feature of the course. So, how is it run?

Running the project

First and foremost, a lab is commandeered at this time for priority use by the chemists, ideally with a prep room nearby for technicians’ ease.

In the first lesson, I set the context. Each year this contextualisation is reviewed to ensure it is personalised and/or localised. I then link to the curriculum via red blood cells, and transition metal complexes.

At this point pupils are placed into carefully constructed groups. I usually limit groups to four/five pupils depending on class size and carefully consider a few key aspects to ensure each group is on a fair footing. These include: previous practical ability, confidence with equipment, their attendance and attitude to their learning.

Once in their working groups, pupils are introduced to the food groups they will be examining and choose the one they prefer. Varieties of each food group are also decided by pupils and recorded by the teacher. It is then the pupils’ responsibility to source each sample.

Next, each group is provided with a Great British Bake Off-style technical challenge for the redox titration they will be completing and are reminded of the required practical (making a stock solution and performing a titration) they completed earlier in the year.

Pupils spend the rest of the first lesson trying to fill in the missing information – choosing control variables for their food group and how they will be controlled, what equipment they might use and why, etc. Pupils are reminded to refer to their lab books and practical handbooks if they are unsure of anything at this point.

Some of you may have noticed the direct link to CPACs (Common Practical Assessment Criteria). This is deliberate. While my overall intended outcome for the practical is soft skills development, there is also the development of good planning that concurrently allows pupils to obtain evidence towards their CPAC endorsement at the end of year 13.

At the end of this introductory lesson, pupils are provided timetables for when the lab will be available – both during scheduled lesson time and frees in which teachers have agreed to supervise.

However, pupils are told next to nothing about this practical before this first lesson, other than it is the introductory lesson to an extended investigation having to do with iron. To help reduce stress and aid their planning, pupils are given a general idea of how long specific aspects of the practical may take, i.e. one lesson to create stock solution, one lesson to refamiliarise themselves with titrations technique and achieve a rough titre, and several lessons to achieve concordant results.

Pupils are also reminded that each food group has its own challenges so communication between group members is essential. As such, they are advised to exchange contact details so that group members can easily communicate with each other and arrange to return to the lab quickly after creating stock solution to start titrating. There are in-school technology solutions to help this communication, but we also provide an in-tray for each group in the lab for notes.

Risk assessments and lab use

I have found that many pupils will do a risk assessment via copy and paste. Few seem to understand that a risk assessment is to keep both them and others in the lab safe. This understanding of joint responsibility for safety is hammered home in the first session.

On that first day “taking over” the lab, the technician walks pupils through the adjoining prep room, outlining where possible equipment they may want to use is located, where work can be stored and expectations for its overall upkeep. Moreover, access to the lab is only available when it can be adequately supervised by a chemistry teacher.

The first few hours in the lab are spent helping pupils get started, answering questions, etc, but by the fourth/fifth hour pupils have usually got the hang of things. Finally, before beginning, a maximum lab capacity is decided based on the equipment, chemicals and method required to carry it out. Once the lab is full, a “one-out, one-in” policy is enforced.

The results start to come in

Once results are collected, pupils are provided the stoichiometry of the reaction to aid their calculations and each group prepares a 10-minute presentation that must answer three questions:

  • What difficulties were experienced and how were they overcome?
  • Which of the varieties that were tested would they recommend and why?
  • What are the cost implications of the recommendation?

Pupils must provide hand-outs of their calculations and conclusions for every person in their class. These help stimulate peer-evaluation and aid in pupils’ final recommendation, considering every group’s results. When I collect their lab books, I am looking for CPAC evidence, well laid-out calculations and a justified, support conclusion.

The project has a variety of positive results. It builds a community of A level chemistry students and allows the less academic pupils to shine. It also opens some pupils’ eyes to alternative pathways after A level. Pupils develop increased confidence – they are more willing to ask questions of each other and myself. It helps pupils to build communication skills, resilience and perseverance, too.

Top tips

Do not be afraid to try it. It is very scary to try something as big as this, particularly if you have never done it before and you do not have somebody to support you, but the gains far outweigh the risks. A supportive, collaborative group of colleagues makes it even easier.

You need to know your students fairly well to be able to divide them into appropriate groups for the project. As such, it is probably unwise to attempt it any earlier than the summer of the first sixth form year.

Do not reinvent the wheel – start from an example, perhaps from Salters or Nuffield, and expand that. Likewise, be prepared for about a week of work to do the preliminary investigative work and prepare introductory resources.

Further information & resources