Image of a woman's face as she is putting on her makeup - Image du visage d'une femme en train de se maquiller - cosmetics and Science in Schools
RF Dreamstime

What influences decisions when buying cosmetic brands? Are we influenced for example mostly by cost, brand reputation or loyalty, celebrity endorsements, ingredients, or testing regimes?

Subject: Cosmetics

The resources in this unit will provide opportunities for your students to investigate links between science and society and to develop their practical skills by using everyday ingredients to make their own cosmetics in the form of an exfoliator crub, and/or a bath bomb.

The science behind exfoliation

The skin undergoes a natural exfoliation process called keratinization. The live cells at the bottom of the epidermis (top layer of your skin) work their way up through the other layers, becoming harder as they reach the top of the surface. At the top, these cells die and flake off revealing the newer, healthier cells underneath. Our exfoliators help to slough away those dead skin cells, unclog the oil and dirt in our pores, and leave our skin looking healthy and rejuvenated.

The science behind bath bombs

The effervescence is gas being released from an acid-alkali reaction between two of the ingredients in the bath bomb. The baking soda (sodium bicarbonate) acts as an alkali, reacting with the citric acid to produce carbon dioxide gas, water and a neutral salt, sodium citrate. This reaction is endothermic, which means that it takes in energy. Because carbon dioxide gas is being released into the environment the mass of the reaction goes down throughout and the bath bomb dissolves into the water amidst the bubbles.


  • To carry out research about cosmetics advertising and analyse reviews.
  • To learn about the use of natural chemicals in the manufacture of skincare products.
  • To develop practical skills in Science.
  • To learn some technical terms in Biology and Chemistry and practise reading and writing technical English.

Age range:


Curriculum Links:

Science, Chemistry, Biology, English, Media Studies, Personal, Social and Health Education

Preparation needed:

You will need:

  • Access to the internet, magazines, large pieces of paper, post it notes, various everyday, natural ingredients (see recipes).
  • Mixing equipment such as bowls, forks and spoons, measuring cups, scales. The bath bomb procedure uses a spray bottle like those used for spraying houseplants.

You will need to:

  • Practise the recipes - depending on your source of the natural ingredients, the exact quantities used and methods may give variable results.
  • Risk assess the use of the ingredients in your classroom.