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: Using the diagram below:
[IMG]
What can be concluded about the relationship between line
$$l$$
and plane
$$P$$
? Why?
What can be concluded about the relationship between planes
$$P$$
and
$$Q$$
? Why?
What can be concluded about the relationship between lines
$$l$$
and
$$m$$
? Why?
What can be concluded about
$$\overline{AB}$$
and
$$\overline{CD}$$
?
Line
$$j$$
lies in plane
$$P$$
, and line
$$i$$
lies in plane
$$Q$$
. What can be concluded about the relationship between lines
$$i$$
and
$$j$$
?


aligns: no