Origami is a little tricky for them because they don't have the dexterity, but with a little help they made origami bookmarks and christmas trees as an activity. They had fun with it. Folded Paper Heart Book Page Marker – DIY
My idea - Each child decorate a hand and attach it to the big tree. (Make paper hand cutouts from your children's hands. Write things they are thankful for on the hands and you will build your own thankful tree!
Place Value Cups. Use the cups to understand place value practice counting forward and backward learn the names of large numbers decompose numbers to expanded form. I would either label the cups 'ones' 'tens' etc. or add a comma cup or decimal point cup
What Makes a Parent Love a Teacher - terrific post by Jennifer of Cult of Pedagogy about the importance of getting to know your students and some tips doing that. More importantly, create positive connections with your students.