standard_description: Add and subtract within 1000, using concrete models or drawings and strategies based on place value, properties of operations, and/or the relationship between addition and subtraction; relate the strategy to a written method. Understand that in adding or subtracting three-digit numbers, one adds or subtracts hundreds and hundreds, tens and tens, ones and ones; and sometimes it is necessary to compose or decompose tens or hundreds.
problem_activity: Problem 1
Katia and Gerard are stocking shelves at the grocery store. Katia stocks 3 shelves with 7 boxes of cereal on each shelf. Gerard stocks 7 shelves with 3 boxes of cereal on each shelf.
Katia says they put the same number of cereal boxes on each shelf. Gerard says they didn’t, since they stocked a different number of boxes on each of a different number of shelves. Who do you agree with, Katia or Gerard? Explain.
Problem 2
Fill in the facts you know on the multiplication table below.
| **           ×          **  | **           1          ** | **           2          ** | **           3          ** | **           4          ** | **           5          ** | **           6          ** | **           7          ** | **           8          ** | **           9          ** | **           10          ** |
|-----------------------------|----------------------------|----------------------------|----------------------------|----------------------------|----------------------------|----------------------------|----------------------------|----------------------------|----------------------------|-----------------------------|
| **           1          **  |                            |                            |                            |                            |                            |                            |                            |                            |                            |                             |
| **           2          **  |                            |                            |                            |                            |                            |                            |                            |                            |                            |                             |
| **           3          **  |                            |                            |                            |                            |                            |                            |                            |                            |                            |                             |
| **           4          **  |                            |                            |                            |                            |                            |                            |                            |                            |                            |                             |
| **           5          **  |                            |                            |                            |                            |                            |                            |                            |                            |                            |                             |
| **           6          **  |                            |                            |                            |                            |                            |                            |                            |                            |                            |                             |
| **           7          **  |                            |                            |                            |                            |                            |                            |                            |                            |                            |                             |
| **           8          **  |                            |                            |                            |                            |                            |                            |                            |                            |                            |                             |
| **           9          **  |                            |                            |                            |                            |                            |                            |                            |                            |                            |                             |
| **           10          ** |                            |                            |                            |                            |                            |                            |                            |                            |                            |                             |
Problem 3
Solve.
a.
$$4 \times 8 =a $$
b.
$$18 = b \times 6$$
c.
$$c= 35 \div 7$$
d.
$$9 = 18 \div d$$


aligns: no