CPD Workshops

Field in a tray

by Fellowship Agency April 28, 2020

This activity was created as part of a Gratnells What’s in my tray? CPD workshop for secondary science teachers and technicians to support practical work and delivery of the curriculum. It can be carried out as a stand-alone activity for students or combined with other activities from the session to form a STEM carousel. If you would like to find out more about running this activity as part of a carousel, take a look at the CPD Workshops section of the Gratnells Learning Room website where you will find further details and example carousels.

It’s not always possible to get out to a green space, or you may be looking for ways to develop your fieldwork skills in preparation for a field trip. Brush up your skills using this Field In A Tray. This activity is based on an original #WhatsInMyTray activity idea shared by Miss Charlie @mxcharlier, KS3/4 Science Teacher, on Twitter.

Learning outcomes

You will be able to:

  • Carry out quadrat sampling.
  • Identify plants in a model habitat.
  • Estimate population size and percentage ground cover based on a sample.
  • Identify limitations of the method and suggest alternative approaches.

You will need (per group of 4):

  • 2 x Shallow Gratnells (F1) tray with lid (use green trays if you have them)
  • 1 x Field In A Tray printed tray insert
  • 1 x A3 acetate sheet or sealed A3 laminator pouch
  • 2 x Dice
  • 1 x Calculator
  • 1 x Fine-nib permanent pen (for set up use only)
  • 1 x Ruler (for set up use only)
  • 1 x Field Studies Council (FSC) playing field plants identification guide
  • 1 x Instruction sheet and tray label
  • 1 x Question sheet
  • Pen or device for recording your answers

This activity also works for individuals or smaller groups, just increase the amount of time allocated to complete it. Once prepared, this activity can be repeated multiple times, reusing the same equipment for each group.


  • Print, cut out, laminate and trim the Field In A Tray inserts. Place it in the bottom of a shallow Gratnells tray, ‘with grass’ option facing up. Tip: Print single sided but, once cut out, laminate the with and without grass options back-to-back to create a reversable tray insert.
  • Trim an acetate sheet or sealed A3 laminate pouch to fit inside the tray. Tip: Use the Field In A Tray insert as a size guide. Draw an equal-sized grid using permanent pen on one side of the sheet, label each axis with numbers. We used 1-6 on the short (y) axis and 1-12 on the long (x) axis.
  • Place the transparent grid sheet on top of the Field In A Tray insert in the shallow tray.
  • Put the two dice, FSC chart and calculator into the other shallow Gratnells tray.
  • Put the tray lids on.
  • Print and laminate (optional) one copy of the activity instructions or view on any device.
  • Print one copy of the question sheet per group or view and edit on any device.

What to do:

  • Remove the tray lids.
  • Identify all five plants present in the field. Use the FSC ID Guide if needed. Write their common names in alphabetical order on your question sheet.
  • Quickly select five quadrat sample areas by rolling the dice in the second tray. Roll one dice to determine the short (y) axis coordinate and both dice to determine the long (x) axis coordinate. Write down your coordinates in the notes area on your question sheet.
  • Use the five sample areas to:
    • Estimate the total number of plant 1 in the entire field.
    • Estimate the total number of plant 2 in the entire field.
    • Estimate the total number of plant 3 in the entire field.
  • Estimate the percentage ground cover of plant 4 in the entire field.
  • Estimate the percentage ground cover of plant 5 in the entire field.
  • Describe the location of the smaller nettle patch.
  • What is the limitation of using dice? What could you use instead?

Tidy up time:

  • Put the equipment back into its original tray.
  • Replace the tray lids.
  • Stack one tray on top of the other.
  • Replace the instructions and activity name sheet.

When all participants have completed the activity, swap answers with another group and mark the answers as the activity leader reads them out or hand your answers to the activity leader for marking.

Example blank question sheet


1 point for each answer.

Must be within 20 of the number of species estimates to get a point.

Must be within 5% of the percentage cover estimates to get a point.

12 points available in total.

  • Plants present 1. Clover, 2. Daisy, 3. Dandelion, 4. Grass, 5. Nettle (5 points)
  • Number of plant 1, Clover = 107
  • Number of plant 2, Daisy = 167
  • Number of plant 3, Dandelion = 81
  • Percentage ground cover of plant 4, Grass = 100%
  • Percentage ground cover of plant 5, Nettle = 13%
  • Describe the location of the smaller nettle patch = North-west quarter OR location given as xy coordinates.
  • The probability of rolling each number (1 to 12) is not equal. Use a random number generator instead or create a new grid with only 6 x 6 squares using dice.

What is happening?

Keywords: Quadrat, Fieldwork, Sampling, Random Sampling.

Sampling methods are used by scientists to determine the size of a given population when it is not feasible or possible to count every single individual. The aim is to select a sample which is representative of the population and to use mathematical formulae to determine an estimate of the entire population in a given area.

Random sampling, the method explored in this activity, assumes that each member of the population is equally likely to be included in any sample. The study area, or habitat, is divided up in to a regular grid. In the field this is often done with long tape measures or using an OS map grid reference depending on the size of the study site. A random number table or random number generator (free Apps are available) is used to select sample sites within the study area. The sample site is surveyed, often using a quadrat (traditionally a square frame often divided into smaller squares), and the total number of species, or specific species of interest, in the sample site is recorded. This is repeated for several sample sites within the study area to gain a representative picture. The sample site data is combined and used to extrapolate, or estimate, the population levels across the entire study site.

Random sampling can be a useful technique to study the biodiversity of a habitat and to investigate how biodiversity and population levels change over time i.e. season to season or year to year. Random sampling can also be used to asses the impact of change on a habitat over time i.e. building work, pollution, contamination or climate change. Biodiversity surveys such as this are usually performed alongside measurements of abiotic conditions, such as temperature, light levels, humidity and wind speed, to get a full picture of the factors affecting the biodiversity of the area.

Other things to try…

  • Use your suggested alternative method for generating your sample coordinates (be sure to select a method that is truly random). Does this alternative method generate different results?
  • Create your own Field In A Tray printable using a blank shallow (F1) tray template from Gratnells. Share your designs with others and re-run the activity to further develop your fieldwork and sampling skills. You could stay with a field design or produce a printable of an alternative habitat.
  • What other materials could you use to create an engaging tray to survey? i.e. not a printed picture. Come up with a few ideas. select one, create or construct it and give it to someone else to survey.
  • Look up alternatives to random sampling, i.e. stratified sampling and systematic sampling. Can you think of example environments or study areas where each method would be best suited to assess the biodiversity?
  • Share photographs of your work on social media using #WhatsInMyTray.

Health & Safety

As with all Gratnells Learning Rooms What’s in my tray? activities, you should carry out your own risk assessment prior to undertaking any of the activities or demonstrations.