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
Simplify
$${\sqrt{8}+5\sqrt{2}}$$
.
Problem 2
Write a radical addition or subtraction problem that cannot be simplified, and explain why it cannot be simplified.


aligns: no