Do you have any ideas on activities I can do with my PK4 children to teach them the concepts of same/different? Thanks in advance.

I don't teach preschool, but here's what I would think... Start with sorting activities. Let's put all the circle blocks (of the same color) in one area and all the square blocks (of the same color) in another area. Stress that you put all the circles together because they are the same. Stress that you put all the squares are the same. Circles and squares are NOT the same. They are different. Then build from there. Graduate to lucky charms. They like to eat those. Then read stories about same and different and see if they can pick out things in the pictures that are the same and things that are different. Put one object in a group of objects that are different. Ask them to point and show which is different. It does NOT belong. Then try some fun worksheets. Let their conversations guide you.

Maybe make shapes, letters, or numbers and mix one in that doesn't belong and have the children pick it out. Or you could have a group of similar toys with one toy that doesn't belong in the group and have the kids pick which is different. Also, you could have the children find matching pairs of socks or mittens. You could sort fall leaves that are the same/different. They could even sort snacks (salty vs. sweet).