Now that kids can order numbers to 10 and count on by adding one or two, it is time to tackle taking away a number or two! This unit introduces first graders to subtraction and number relationships within ten. Students are encouraged to uncover "number mysteries" by identifying what is "one less" or "three less" in a fun and interactive way with colorful animal images. Number bond puzzles ask them to find a missing addend that combines with a given part to reach a target sum. Most problems offer four choices, which encourages quick fact recall and confidence with simple equations. Common Core skills addressed are 1.OA.A.1, 1.OA.C.5, and 1.OA.C.6.