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Chain Reaction

An engaging primary school STEM project for upper KS2 children that is easily adapted to suit any age group.

About the Project

The notion of ‘cause and effect’ is one that comes easily to most children; their own life experiences are likely to have provided many examples. Given a collection of simple toys, perhaps cars, ramp/tracks and dominoes, you might expect that even very young children will explore ways to make a car run quickly along the track to knock over dominoes that have been set up on end, so that these then fall over one by one.

Adding further components to the selection, it soon becomes apparent that it is possible to link more of these actions together - and the concept of a ‘mechanical chain reaction’ develops: the movement of one object leads to that of another and then another; limited by the number of components that are available and the skill of the creator to arrange these in such a way that sufficient energy from one component is passed to the next to enable that object to move.

The ‘Chain Reaction’ project provides children with the opportunity to: design, test and refine their own chain reaction ideas, utilising both D&T and simple engineering skills; explore the science of forces, simple machines and energy transfers, whilst also working scientifically; and many opportunities for further crosscurricular links (some of which will be explored within this resource).

Since its original inception in 2015, the PSTT ‘Chain Reaction’ project has been successfully trialled in over 23 schools. This resource, developed by Sue Martin (Programme Director), is intended as a starting point to explore the possibilities of using cheap, readily available resources to deliver age-appropriate STEM activity. It also supports teachers with background science information and relevant context.

Following the publication of the PSTT trial Chain Reaction Booklet, College Fellows Caroline Galpin and Helen Ellis have extended the resources now offered to schools to include ‘The Matrix’ and a suggested Scheme of Work, each with teacher comments to help others make the most of these resources.

Resources to download:

  • Chain Reaction Booklet – a guide to running a ‘Chain Reaction’ activity/event in school, with background science information and cross-curricular link ideas. This booklet is available to download as a pdf.
  • ‘Forces’ Scheme of Work (aimed at Year 5/upper KS2/9-11 year olds), which demonstrates the way Helen Ellis incorporated the Chain Reaction project into this topic. Details of other teachers’ comments and tips on how they used or adapted the activities have been added to the SOW so their suggestions can by universally shared. The SOW is available to download as a Word file.
  • The Matrix, produced by Caroline Galpin, provides support for activities in the Scheme of Work and beyond. It is organised in eight topic areas, each of which has five levels of progression with suggested practical activities. Teachers in the project used these in lessons, within their Science Clubs and as homework activities. This resources also contains many activities designed to challenge the most able pupils. The Matrix is available to download as an Excel spreadsheet, with hyperlinked activity sheets and background information. The sheets are locked to protect their formatting but may be opened using the password CHAIN. The Matrix also includes useful teacher comments and tips.

Resource Downloads


Full Chain Reaction Booklet [7.18MB]



Forces Scheme of Work [841.08kB]



The Matrix [15.27MB]


Safety Notice and Disclaimer

The PSTT advises teachers to refer to either the CLEAPSS website or SSERC website for up to date health and safety information when planning practical activities for children.

The PSTT is not liable for the actions or activities of any reader or anyone else who uses the information in these resource pages or the associated classroom materials. The PSTT assumes no liability with regard to injuries or damage to property that may occur as a result of using the information contained in these resources. The PSTT recommends that a full risk assessment is carried out before undertaking in the classroom any of the practical investigations contained in the resources.

All materials are ©Primary Science Teaching Trust (PSTT) and are freely available to download and share for educational purposes. Whilst educators are free to adapt the resources to suit their own needs, acknowledgement of copyright on all original materials must be included. Rights to images included in the resource have been purchased for PSTT use only – as such, these images may only be used as part of this resource and may not copied into or used in other materials.



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