standard_description: Add within 100, including adding a two-digit number and a one-digit number, and adding a two-digit number and a multiple of 10, 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 and explain the reasoning used. Understand that in adding two-digit numbers, one adds tens and tens, ones and ones; and sometimes it is necessary to compose a ten.
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.


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