Subtracting with Objects

Mr. Squeaks and Imani have a terrible problem on their hands, they accidentally brought back a dinosaur egg on another time travel adventure! The egg hatched and this little guy is hungry! Imani and Mr. Squeaks started the week off with five trees but the dino gobbled down two! And he keeps on eating!! Let's teach Mr. Squeaks and Imani all about, "Subtracting with Objects", to help them figure out how many plants they have left! Subtracting means taking away one number from another number to find out how many are left. When we subtract with objects, we use touchable things to take the place of the bigger, first number we are subtracting from. This helps us see what happens when we take away an amount from what we first had. In math, we use lots of touchable objects to help us represent numbers like: counters, place value blocks, and math cubes. Today we will use math cubes to help Mr. Squeaks and Imani. Right after hatching, Baby Dino gobbled down two of the five trees outside. If we solve five minus two, how many trees are left? Let's try subtracting with objects to help! To start, we use math cubes to show the bigger, first number, five. Then, we look at the second, smaller number, two. This tells us to take away, or subtract, two cubes from the five that we have. Now, count the cubes that are left: one, two, three! Three is the answer, so we write it next to the equal sign. There are three trees left. Next, Baby Dino chomped down four of the eight bushes! If we solve eight minus four, how many bushes are left? Begin by using math cubes to show the bigger, first number, eight. Then, we look at the second, smaller number, four. This tells us to take away, or subtract, four cubes from the eight that we have. Now, let's count the cubes that are left one, two, three, four! Four is the answer, so we write it next to the equal sign. There are four bushes left. Oh no! It looks like the little guy has nibbled off five of the ten ferns now. Let's figure out how many ferns are left if we solve ten minus five. How many math cubes do we need to show the first number? Ten! Now, look at the second number. How many math cubes do we need to take away? Five! What number do we get when we count the cubes that are left? Five! Finally, write five after the equal sign. While Mr. Squeaks and Imani hatch a plan to take back their little friend, let's remember! Today we learned about subtracting with objects. Subtracting means taking away one number from another number to find how many are left. When we subtract with objects, we use touchable things to take the place of the bigger, first number we are subtracting from. To subtract with objects: Use math cubes to take the place of the first, larger number. Then, look at the second, smaller number, to know how many cubes to take away. Finally, count the cubes that are left and write your answer next to the equal sign. "Oh thank goodness this plan worked!" "He nearly ate us out of house and home!" "You mean he nearly ate our house and our home!"