Entry #3: Colouring pictures in GeoGebra 🖌️

 Colouring pictures in GeoGebra

When I wrote yesterday's post, I started to think about ways to improve it. And... eureka! 💪😀 The inclusion of the images with the coloured figures was quite good, so... why not make a tutorial of how I did it so that you can do the same with your students? Then, if you are interested in knowing how to colour pictures, you are in the right place, read on! 👀🖌️ 

1. Downloading GeoGebra

The first thing that you must do is downloading GeoGebra. In order to do that, you must click on the following link (click here!). Then, you will find the webpage, where you will be able to download GeoGebra Classic 6. There are more apps, but this tutorial will be focused on that one 😉. 

Easy, right? Let's move on! 😄

2. Starting GeoGebra and downloading an image

This step is quite easy, you only need, first, to start GeoGebra. 👉 For that, the downloaded file must be used 👈. Then, once you have done this, you should download the image that you want to use or choose it from your device. I will use the following image:

3. Opening the image in GeoGebra

From this moment we are going to work in GeoGebra. First of all, I recommend you click on the right button of the mouse and uncheck the options of grid and axes 🖰, since we are not going to need them for this activity. Then, in order to open the image, you have to follow the next path: 

4. Creating the shape

Once we have opened the picture, we must start to create the shape that we want to colour. For that purpose, we must choose the following tool: 

This tool is used to create polygons. Of course, we will create a pyramid, which is a polyhedron, but, as we remember, the faces of polyhedra must be polygons, so we can use this tool to build the faces! 👏 To do this, points are placed at the vertices, so that they are joined by segments, which will be the edges of the polygons of the faces. This can be seen in the following screenshot:

As you may see 👀, a triangle has been generated. From this moment, we can do the same thing with the other visible face of the pyramid. So far so good, let's keep going! 😀

5. Colouring the faces

Now, it is time to colour the different faces of the pyramid 🖌️. In order to do that, we are going to look for the polygons in the left column. Once found, we must click on the three buttons and do the following: 

Now, we are going to click on "Colour" in the pop-up window. Here, we can choose the colour of our face. After this, we must go to opacity and include the amount of it that we like 👍. 

From this moment, we could finish the edition. However, before explaining to you how to save the image, I will give you some optional steps which are interesting in order to make the picture look better 😏. 

6. The hidden edges!

If we want our students to better understand a solid like this, it is convenient to draw the hidden edges. For that, we are going to choose the option of putting a dot (the second option of the toolbar), and we are going to place them on the hidden vertices. 

Then, we are going to choose the option "Segments" in order to join the different dots. These are the hidden edges of this pyramid. However, it would be nice to mark in some way that these edges are hidden 😋. To do that, let's make those segments discontinuous. So, we click on the right button of the mouse over the hidden edges. Then, we select "Settings". Once there, we go to "Style" and in "Line Style" we choose the option that we like the most. We must do the same with the other hidden edges.

If you want, in order to make all the edges look the same, we can change the colour of each of them by following the same path as before but choosing the option "Colour" 😉. I have decided to colour all of them in red. From my point of view, this will be useful for students to see the edges in an appropriate way! 👦👧

7. Hiding objects and labels

As you may have realised, we have many dots and labels on the picture. So, if we want to improve it, it would be convenient to hide them. But how? 😅 Well, hiding the dots is quite easy. In order to hide them, we only have to click on the circles of each dot that we can find in the left column. Finally, to hide the labels of the edges, we must click on the right button of the mouse on them and uncheck "Show label". 

8. Exporting the image

Now, we must click on "Export Image" to download it. Maybe, it will not be downloaded in an appropriate file format, so you must change it by modifying its name and adding ".png" at the end. 

And here we have the final result! 👇😀

That's all! I hope you have found this tutorial useful. Here I leave a video in which it shows how we can change the colours of our shapes in GeoGebra! See you in future posts! 😁