An analog clock with the visuals that support counting by 5s is most useful to have in a classroom to support students in Tier 3. Whether its taped up by your clock, or posted on the wall, or printed on as flash card on a desk; it's mindful of the students that struggle more with time.
This reference chart is a fun way to present a visual for students for both spelling and order of days when writing, reading, completing math story problems, etc. Tier 3 students benefit from quick references around the room to help support moments when they can't rapidly recall information yet.
Place Value Chart interactive for dry erase capability up to three numbers. This is meant for a third grade classroom covering ones through thousands. For students in Tier 3, this is a great chart to have when finding place value, comparing numbers, and rounding.
As a moving resource teacher, sometimes compact items are needed to reduce the amount of materials moved from room to room. I have a set of these in a zip lock inside a binder I carry around. Not only is it fun and colorful, but in downtime and needing an activity to pull out, it is also a puzzle of its own.
Flat counters are handy as a moving resource teacher who carries a lot of things from room to room. Also, as a side activity, the counters create a fun and colorful puzzle.