This website, https://primefactorisation.com/zukei/, is great if your class is learning about properties of shapes and allows you or your students to create a puzzle whereby others have to find certain shapes from a given set of points.

To start with, you are given a blank grid which can be increased or decreased in size:

Next, click on a set of points (random or otherwise!):

If you then click on one of the choices (e.g. square as shown above) it will show you all the possible squares that can be drawn with this set of points (in this case none).

Clicking on ‘right triangles’, however, will reveal three possible answers:

Clicking on a choice that has no possible answers (e.g. square in this case) clears all the previous lines which then allows the teacher (or student) to capture the image to be used. In this way, you can show the set of points and ask ‘How many right triangles can you find?’ These puzzles are great in helping students rethink their definitions of geometric properties. For example, some students think that rectangles are only ever oriented horizontally (or vertically!) so will benefit from a puzzle like this: