The pair – who split in 2015 – is both trying to work together and co-parent their family.
A source revealed: "Ben had Good Friday off from filming and spent the day with the kids. They went and saw a movie and then had shave ice and milkshakes after.
"The kids were happy to see Ben and were holding his hand and hugging him. Jen seemed happy for the kids and stepped back to let Ben have his time with them."
RadarOnline.com reported how Affleck has been flying back from Hawaii where he is currently filming 'Triple Frontier' to take his family to church.
Garner, 45, has been posting images on her Instagram going for hikes in Hawaii while Ben has been watching their kids.
A source added: "They have been hanging out as a family, but Jen has also given Ben alone time with the kids. On Saturday morning, Jen left the kids with Ben and went hiking at Koko Head Trail with her trainer.
"The hike took Jen over an hour, but she was in great shape and walked very quickly up the stairs to the top. She admired the great views before heading back down. Ben and the kids relaxed at home while Jen was gone."
It's understood that Affleck, 45, has rented a house while he is filming and that Garner is staying in nearby hotel.
We pay for juicy info! Do you have a story for RadarOnline.com? Email us at firstname.lastname@example.org, or call us at (866) ON-RADAR (667-2327) any time, day or night.