Teacher's Guide

Visitor Tracker

  • Stages: Grade 7 to 10
  • Time estimate: 150 minutes (2 to 3 sessions)


This activity takes us through the conceptualization and development of an app to monitor visitors in a shop, or another place, using a micro:bit card.

The guidance follows the steps taken in a real app or physical computing project. During the activity, students will initially analyse the problem to brainstorm potential solutions, with their pros and cons. The solutions will rely on concepts like variables, sensors, acceleration and radio wireless communication.

Teaching strategy

The activity is presented in a way in where the problem analysis, the chosen solution and the device building are different key stones. All these stages are open to debate.

In a large class, the different stages can be discussed by the whole group. Then, the whole group can unite efforts and take a single direction, or students can be divided in smaller groups that should try the different solutions.

The aim is to socially share the ideas and insights to solve the activity. It should enhance the group's collaboration and creative skills.

Analysing the problem together

Initially, the activity analyses and explains how to count the number of visitors without looking at the programming or building stages, just as a mathematical question. It requires to understand the actions that a visitor performs when coming to the shop.

At this point, it can be creative and funny for the students to imagine situations in where our analysis would fail; when two customers get in together, the postman brings the mails, a client who is leaving opens the door to let someone in and gets out without closing,… All these situations would break our solution. Can they think of real life examples? Automatic doors opening every time a bird passes by?

Choosing a solution

As stated in the activity page, the activity can be performed using different mechanisms.

At this stage, the conceptualisation of the mechanism is based both on creativity, and on the knowledge of what a micro:bit board and its sensors can do.

The different options to perform the activity could be discussed with the students. The class can be asked to open a debate and bring up ideas and concerns, and start planning how the physical design of the device could be. Different groups can work on each one of them to organise a final debate and choose the best proposal.

This is a common situation in programming and physical computing; often there are different solutions to solve a problem, and a team needs to investigate to decide what direction to take, with its pros and cons.

Building the device

In order to build the device, the students will have to design it first. To do so, they should keep in mind what they analysed in the previous steps.

Once again, there are different ways to approch this and they can be discussed.

During the build process, the activity uses several blocks that aren't required for the program to work. They are helpful to understand its functionalities and how the sensors report to the board. say, display or graph blocks are useful to understand what is going on behind the scenes and debug our scripts.

Testing is essential, and it can be pointed out just by asking the students what records they expect from the sensors prior to seeing them. And depending on what sensor they are using, play a game to check what group gets closer.

The more data students have, the more accurate the device will be. Collaborating and sharing their results will be beneficial for the whole class.


As we have seen, the idea behind this activity is to discuss and solve a real problem that has different solutions. It is likely that the longest part of the activity is to analyse the problem and imagine the different approaches.

Thinking of these different solutions and how to achieve them is part of a creative process. It is the key stage that will define the guideliness of the technical process that takes place afterwards. The overall process is a standard strategy in professional computing.

There are different approaches to perform this in a class. By dividing the class in smaller groups, students can research the ups and downs of the option assigned to them and share their conclusions with the class. Their work will help the whole group to take an agreed decision. Or they could reach the conclusion that it is better to bring to life two different devices. The path is open.

The activity isn't technically difficult, although it uses several concepts like variables, loops, and sensors. But the highlighted feature is the creative solution and team work.