This is a super popular activity for seniors of all abilities. This works really well for people even in moderate stages of dementia since common phrases are something they often still remember. I'm often amazed at how the person can't remember their children's names, yet they can remember the ending of a popular phrase.
This activity can be done in many different ways. I often facilitate it as a group activity and allow participants to call out the answer. If you find that there are a lot of different cognitive levels in the group, ask the higher functioning participants to allow others to have time to think of the answer. My experience is the higher functioning participants understand the reason for giving others a chance to answer so it makes it enjoyable for everyone.
I also facilitate this activity one-on-one with patients with dementia. I will start the activity by using very popular phrases such as 'Out of sight, out of mind'. When doing the activity, I might say, 'Out of sight, out of ?' and give the person time to answer. If they don't answer, I'll try another 2-3 phrases to see if the person can think of the answer. If they don't answer, I know the activity is too challenging for them or it's not a good day and I'll try again another day. If the person does answer several of the phrases correctly, I might make it slightly more challenging by giving less of the answer (for example, 'out of sight, ?'). The main thing when working with people with dementia is to make the activity fun, and not too challenging. You definitely do not want to frustrate the person. If they appear to be enjoying it, you can continue but if they appear tired or show or say they don't want to continue, then stop the activity immediately.
For participants with mild dementia or for seniors in general, you can also ask if they know the meaning of the phrase. It's a great opportunity for a social and cognitive activity.
I have attached the Word document with the proverbs and idioms. Feel free to use with your loved one, or in a group setting with seniors at retirement, nursing or senior day programs.