In this challenge, students can code an app to determine the rules for addition, subtraction, multiplication or division of two integers.
After building this Scratch app, have students run through a set of different numbers and record their observations (e.g.: multiplying two negative numbers yields a positive product). From here, have them determine appropriate rules for addition, subtraction, multiplication and division rather then you telling them. It may take some time for them to make a conclusion, but that in itself is a mini Science lesson.
Feel free to use the source and extend it for three or even four integers.
Here is the demo:
Project page: https://scratch.mit.edu/projects/121099775/
In the next class, have students determine “why” the rules are what they are (e.g.: using temperature or money). This would provide a great opportunity for observation and conversation in terms of assessment.