Mental Math ~ 10 more, 10 less

The students are getting very proficient at place value concepts.  They have been working so hard.  We have now moved to adding large numbers with in 100.  You would never guess that they are first graders with how they add, subtract, and build tens.  They are amazing.  Before getting in the thick of double digit addition and subtraction, we are building some mental math fluency by taking a number and quickly knowing 10 more, 10 less, 1 more, and 1 less.     To build this mental math quickness we practice in a variety of ways.  For example, we have been solving different number mazes.  The children start at a particular number, in the example to the left it was 34.  The path to the next step gives a direction: 10 more, 10 less, 1 more, or 1 less.  Each time a new direction is given the students have to model the action on two reflected iPads (pictured below).  One iPad has base ten blocks to model the numbers, additions, and subtractions with manuplatives.  The other iPad has a 100s chart to flip the number path.  Students quickly discovered numbers moved to the left for one less, to the right for one more, to the top for ten less, and downward for 10 more.  At the end of the maze, the students discovered the "secret number." 

   The students really worked well as a team to read the clues, act out the additions and subtractions, and write down the numbers on the maze.  Such impressive thinking. 
    Of course, we have a partner game for every important math concept!  When students were doing well whole group, the concept of mentally adding and subtraction ten went into a partner game.  In this game, student uncovered a number at the top and then had to add or subtract 10 to cover and number on their game board.  The first player to get three in a row won the game.  Look at the concentration!

 

 Certainly part of the students' success and achievement with place value has to be the apps and online computer games.  The ipads and computers provide such engaging independent practice.  Further, the apps give the children immediate and specific feedback about their math work.  The apps also allow the students to work at their exact level, pushing and strengthening their conceptual knowledge right where they need it.  For this particular standard, a great app has been Mystery Number . The app contains four different games that give students lots of opportunities to explore concepts of number and place value.  The game "More or less?" practices ten more ten less.