standard_description: Add and subtract within 20, demonstrating fluency for addition and subtraction within 10. Use strategies such as counting on; making ten (e.g., 8 + 6 = 8 + 2 + 4 = 10 + 4 = 14); decomposing a number leading to a ten (e.g., 13 – 4 = 13 – 3 – 1 = 10 – 1 = 9); using the relationship between addition and subtraction (e.g., knowing that 8 + 4 = 12, one knows 12 – 8 = 4); and creating equivalent but easier or known sums (e.g., adding 6 + 7 by creating the known equivalent 6 + 6 + 1 = 12 + 1 = 13).
problem_activity: Problem 1
Explain how you know the expressions in Column A are equivalent to the expressions in Column B.
{"table": [{"_attributes": {"class": ["table", "table-bordered"], "style": "width:70%"}, "tbody": [{"tr": [{"td": [{"_attributes": {"style": "text-align:center"}, "strong": [{"_value": "Column A"}]}, {"_attributes": {"style": "text-align:center"}, "strong": [{"_value": "Column B"}]}]}, {"td": [{"_attributes": {"style": "text-align:center"}, "span": [{"_attributes": {"class": ["math-tex"]}, "_value": "$${-3(x+4)}$$"}]}, {"_attributes": {"style": "text-align:center"}, "span": [{"_attributes": {"class": ["math-tex"]}, "_value": "$${-3x-12}$$"}]}]}, {"td": [{"_attributes": {"style": "text-align:center"}, "span": [{"_attributes": {"class": ["math-tex"]}, "_value": "$${(4+x)+3}$$"}]}, {"_attributes": {"style": "text-align:center"}, "span": [{"_attributes": {"class": ["math-tex"]}, "_value": "$${x+(4+3)}$$"}]}]}, {"td": [{"_attributes": {"style": "text-align:center"}, "span": [{"_attributes": {"class": ["math-tex"]}, "_value": "$${(x+4)-3}$$"}]}, {"_attributes": {"style": "text-align:center"}, "span": [{"_attributes": {"class": ["math-tex"]}, "_value": "$${-3+(x+4)}$$"}]}]}]}]}]}
Problem 2
Explain the properties of operations that were used to transform
$${a(x-y)}$$
to the equivalent expression,
$${-(ay-ax)}$$
.
Problem 3
If the expression
$${\frac{x}{2} + \frac{3}{4}}$$
is multiplied by
$$4$$
, the expression
$${{2x+3}}$$
results.
Is
$${{2x+3}}$$
an equivalent expression to
$${\frac{x}{2} + \frac{3}{4}}$$
?


aligns: no