Task your students with using different addition strategies to solve the case with this engaging detective activity.
Using Mental Addition Strategies to Solve the Case
Looking for an engaging and exciting way to teach addition strategies in your classroom? This maths investigation transforms learning into a mystery your students will be eager to solve.
A bank has been broken into, and a large sum of money is missing. Students must use their mental addition strategies to uncover clues, eliminate suspects and crack the case. As the classroom transforms into a detective studio, students step into the role of addition detectives, complete with their own suspect wall and a growing collection of clues. Each challenge encourages students to apply a variety of addition strategies while working through a very suspicious crime.
Addition Detectives to the Rescue
The Addition Detectives PowerPoint includes 43 engaging slides, all designed in a detective‑themed storyline to capture students’ attention from the very first slide. The presentation leads students through seven mini-investigations, each focusing on a different mental addition strategy.
In every investigation, students are introduced to a clear example of the strategy before solving a related problem. Once the correct answer is revealed, a suspect is uncovered, gradually narrowing down the list as the case develops.
Throughout the investigation, students will practise strategies such as using concrete materials, bridging to ten, the jump strategy, number boards, split strategy, linking addition and subtraction and the compensation strategy.
The investigation concludes with a final set of questions designed to help students identify the innocent suspects and reveal the true criminal.
Download and Go
This ready‑to‑use resource is just one click away. Using the drop‑down arrow on the Download button, you can access all three components needed to run the activity smoothly in your classroom: the PowerPoint investigation, a practise worksheet and a Suspect Board Display. For best results, set up the suspect board display before starting the activity so students are fully immersed from the beginning.
More Great Addition Strategy Resources
If you’d like to explore addition strategies in greater depth, you may also be interested in the following teaching resources:
[resource:3600518] [resource:3602914] [resource:3602994]












This is awesome! Kids love it! Is there a Subtraction Detectives?
Hi Julie Thank you so much for your lovely comment! We're so glad your students are enjoying the resource. At this stage we don't have a Subtraction Detectives resource. Please feel free to make this suggestion at our 'Suggest a Resource' page. https://www.teachstarter.com/au/suggest-a-resource/
I love this! I am a bit confused as there are two Suspect 4's but only one with an identity. Have I missed something??
Hi Gaynor, Great to hear that you are enjoying the Addition Detectives PowerPoint! There should only be one Suspect 4 section. It focuses on using a hundreds chart when adding numbers. I have checked the current download and it is all correct. I'd suggest re-downloading the resource. If you wish, send an email to [email protected] and we will be more than happy to help you figure out what is happening with Suspect 4!