Identikit of Common Substances

Detective needed!

Seven crystal structures are wanted! They are hiding in plain sight in our houses: can you help us find them?

To complete this task, you will need to fill in an identikit of these structures, by accessing our database of crystal structures, the Cambridge Structural Database (CSD). The information you will retrieve from there will be fundamental in finding the seven runaway structures!

Get your detective hat ready and let’s write some identikits!

Once you found one or more of the wanted structures, a reward will be waiting for you! Please, ask an adult to download collectable virtual badge for this activity from this webpage.

What You Will Need:

At the bottom of this page, you can find downloadable, printable resources to guide you through the activity. These include:

  • Guidelines for activity leaders: A resource for the activity leader (adult) to guide the activity, from the setting to the final reflections. This also includes ideas on how to carry out the activity in teams. Please read this document well, before starting the activity.
  • Pick a refcode and search the CSD: The list of refcodes of the substances under investigation. Refcodes are the code names we use to identify each crystal structure in the database. Instructions on how to find the information you need in the database are also included in this document.
  • Activity Worksheet – Identikit: An identikit answer sheet for the detectives to fill in.
  • Six handouts about the common substances.

You will need an internet connection to visualise the molecules in each substance on the CCDC website, which can be done on a phone, tablet or computer. You can access these structures pages either with a QR code scanner or using the search function in the Access Structures page (explained in detail in the Pick a refcode and search the CSD handout). A direct link to the structure is also provided in the “Useful links” section at the end of this page.


To display (and find) the common substances and allow you to match the substance with the molecule, you will need:

  • An empty aspirin (or any drug brand containing acetylsalicylic acid) box. Important – make sure to ask an adult to remove the tablets first.
  • Chocolate
  • Sugar
  • Lemon
  • Caraway seeds
  • Mint flavoured sweets
  • A table tennis ball


Do not worry if you don’t have any of these, you can still do the activity! We would however recommend trying to collect some of the common substances, as the hands-on experience can aid learning.

Learning Outcomes:

In this activity you will:

  • Learn what chemical elements make up some common substances.
  • Learn about the chemical properties and the uses of some common substances.
  • Learn what the CSD is and find different ways to search structures in it.

Recommended age:

  • The learning online is suitable for ages 8+ years with adult supervision.

Health & Safety:

These activities are carried out at your own risk.

Please read these health and safety guidelines to reduce risks:

  • Children should not be left unsupervised with medicines or any small items that could be harmful to ingest.
  • Any access to the internet from minors should be done under adult supervision.
  • If you print and cut out the handouts and reward badge, please be aware of potential cuts from scissors or papers, and irritation from contact of glue with eyes, skin, hair or ingestion.
  • If you structure the activity like a scavenger hunt, be aware of additional risks related with kids running around.

Our Downloadable Educational Resources


In this section you can find the activity leader guide (Guidelines for activity leaders), the identikit worksheet for the detectives (Activity Worksheet – Identikit), the refcodes list with the instructions on how to search the CSD (Pick a refcode and search the CSD), and six common substances handouts.

To start with the activity, follow the direction in the Guidelines for activity leaders file.

Have fun with the investigation!

Find out more

An additional molecule and a simplified version of the handout are available from the activity “Molecules at Home” from the Crystals Adventures.

Classroom teaching module: structure exploration

This module was developed for use in the classroom based on hands-on exercises used at the Cambridge Science Festival.  Thanks to Louise Dawe (Wilfrid Laurier University) for assistance with curriculum benchmarking. Suitable for ages 16+ years.

Useful links

Access Structures page

Crystal structures:

  • ACSALA, view
  • CITRAC10, view
  • JEMSAW (DOI: 10.5517/ccp4csy), view
  • RERXIV (DOI: 10.5517/cc4f8ld), view
  • RERXOB (DOI: 10.5517/cc4f8mf), view
  • SUCROS01 (DOI: 10.5517/cc584yh), view
  • UGAHUF (DOI: 10.5517/cc5s9rz), view
  • KOSNIS (DOI: 10.5517/ccdc.csd.cc20pqt8), view

You can refer to this page for tips and directions for viewing structures in the 3D Visualizer.

Elements in Crystals page, specifically elements carbon, hydrogen, and oxygen

Learn about polymorphs in the Lego, Chocolate and Polymorphs activity.