Work in groups of three or four. Your partner will tell you about something they are likely or possible to do in the future. Tell them one consequence of that, e.g. “If you eat pork for lunch, your stomach will feel heavy all afternoon”. Another person in your group will then make up some consequences of that, e.g. “If your stomach feels heavy all afternoon, you’ll fall asleep at your desk”. Continue for four or five stages or until you run out of ideas, then the original person should say how realistic they think the final consequence and intervening stages are.
Ideas for future things to talk about
Times
Later today
Next week/ month/ year
(With)in the next week/ month/ year
The day after tomorrow/ The week after next
This evening/ Tonight
At/ By the end of…
At + time
On + date
In + month/season/ year
In + number of days/ weeks/ months/ years etc in the future
Topics
Date
Appointment
Meeting
Eating out
Appearance
Work
Study/ Qualification
Exercise
Accommodation
Money
Relationship
Hobby
Entertainment
The arts
Location
Holiday (= Vacation)/ Day off/ Public holiday
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PDF version for easy printing: FirstConditionalConsequences
More first conditional games/ worksheets here.
TEFLtastic 
Second conditional consequences here: https://tefltastic.wordpress.com/worksheets/grammar/conditionals/2nd-conditional/2nd-conditional-consequences/