There are several ways to draw graphs in Scratch. The method we used this week make use of a sprite that consists of a single dot we painted. Using the formula y = mx+c we looped through all x values from -240 to 240 and calculated the corresponding y-values. After moving the sprite to each co-ordinate, the sprite stamped an image of itself making dots that forms the graph. The result shows how the dots are made one by one to create the graph:
The same method can be used for parabolas. In grade 10 they only do y = a*x*x+c
Note that two different types of loops can be used.