Building Numbers in Different Ways (11-20)Play this 1st grade math lesson
Using our mathrack virtual manipulative, students learn that you can build the same number in several different ways, e.g. 10+3 = 7+6. Students can use a variety of strategies to solve these problems, including the commutative property (10+4 = 4+10), doubles or near doubles (10+4 = 7+7), and more. You can also view the mathrack tutorial.
Comparisons with More and Less SymbolsPlay this 1st grade math lesson
Using the hungry alligator metaphor and starting with smaller numbers (1-10), students focus on using the symbols correctly. First graders focus on comparing numbers up to 100, but as they advance they can compare higher numbers. Then students are challenged to understand the values of numerals based on their place in the number. (For example, 587 and 578.) Eventually the alligator is removed and only the symbols remain. Other DreamBox lessons let students build their own comparisons using both virtual manipulatives and numerals.
Number StringsPlay this 1st grade math lesson
A "string" is a set of related problems used to highlight the relationships between problems. This particular strings lesson uses "10s facts" (such as 10 + 4) to solve "9s facts" and "11s facts" (such as 9 + 4 or 11+ 4). Other strings lessons focus on doubles, near doubles, "8s facts," and "12s facts".