Check boxes, variables and math

Hello. I am working on an activity in Storyline 360, where the learner can check off check boxes to add/subtract values to a total (the total is a variable). It is set up so that there are 5 pairs of check boxes, each pair is a button set (so you can only choose one box in each set). As you select a box in each pair the total is adjusted.

I was able to set it up so that when the learner toggles between the boxes in a pair it will adjust the total correctly. Yay!

However, I cannot seem to figure out how to prevent a user from checking the same box repeatedly. When that happens, the total keep getting adjusted. I would like to somehow set it so that once a box is checked it cannot be checked again. I tried setting conditions but that did not work. I also tried creating a true/false variable to control the checkbox but that approach was also unsuccessful. I am pretty sure I am overlooking something obvious. 

I have attached the slide. Any ideas are most welcome.

Thank you!

4 Replies
Adena Wilson

Hello Wendy. Thank you so much for looking at this issue. Using the disabled state does not seem to work in this case. I can still click on the checkbox and the math gets wonky.  I am not sure why.  But I 100% appreciate your offering to help. Below, it looks like Michael has figured it out and he takes a totally different approach. For sure an approach that I would not have thought about. 

Cheers - Adena