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Saturday, February 3, 2018

Frequent addition and subtraction situations - Problem Solving


I would like to share with all of you a table with frequent addition and subtraction model situations that second and third grade teachers are using with the students for problem solving. It is important that our students be exposed to the comparative language in Math as well as they need to understand the meaning and how the vocabulary is related with the operation used depending also of the context situation. I am not saying that we need to teach key words. It is a great pedagogy mistake and it does not help the students to develop their thinking skills.
Me gustaría compartir con todos ustedes una tabla con situaciones frecuentes de modelos de suma y resta que los maestros de segundo y tercer grado están usando con los estudiantes para resolver problemas. Es importante que nuestros estudiantes estén expuestos al lenguaje comparativo en matemáticas, así como también que entiendan el significado y cómo se relaciona el vocabulario con la operación utilizada, dependiendo también de la situación del contexto. No digo que tengamos que enseñar palabras claves. Es un gran error pedagogco y no ayuda a los estudiantes a desarrollar sus habilidades de pensamiento.


Result Unknown
Change Unknown
Start Unknown
          
             
             Add
Last year, Mrs. Rojas bought 235 math books. This year she buys 548 more books. How many math books does she have now? 
              235 + 548 = ?

   
Last year, Mrs. Rojas bought 235 math books. This year she bought some more. She now has 783 math books. How many books did she buy this year?
               235 + ? = 783
Last year, Mrs. Rojas bought math books. This year she buys 548 more books. She now has 783 math books.  How many books did she buy last year?
    ?   + 548 = 783


Take Away
520 pencils were in a box. I used  128 pencils. How many pencils are in the box now?
           520 – 128 = ?
520 pencils were in a box. I used some pencils. Then there were 392 pencils. How many pencils did I use?   
                  520 - ? = 392
         
Some pencils were in a box. I used 128 pencils. Then there were 392 pencils. How many pencils were in the box? 
                      ? – 128 = 3 92     

Total Unknown
Addend Unknown
Both Addends Unknown


Put Together / Take Apart
120 third graders and 103 second graders are in the cafeteria.
How many students are in the cafeteria?
         120 + 103 = ?
223 students are in the cafeteria. 120 are third graders and the rest are second graders. How many students are second graders?
   120 + ? = 223 ,   223 – 120 = ?
There are 223 students in the cafeteria. How many students can be second graders and how many can be third graders?   
 Variety of answers
      120 + 103 = 223
      100 + 123 = 223 , etc

Difference Unknown
Bigger Unknown
Smaller Unknown


Compare
How many more version
Luis has 345 soccer cards. Kenneth has 544 soccer cards. How many more soccer cards does Kenneth  have than Luis?

How many fewer version
Luis has 345 soccer cards. Kenneth has 544 soccer cards. How many fewer soccer cards does Luis have than Kenneth?

345 + ? = 544       ,     544 – 345 = ?
Version with more
Kenneth has 199 more soccer cards than Luis. Luis has 345 soccer cards. How many soccer cards does Kenneth have?
Version with fewer
Luis has 199 fewer soccer cards than Kenneth. Luis has 345 soccer cards. How many soccer cards does Kenneth have?
345 + 199 = ?   ,    199 + 345 = ?
Version with more
Kenneth has 199 more soccer cards than Luis. Kenneth has 544 soccer cards. How many soccer cards does Luis have?

Version with fewer
Luis has 199 fewer soccer cards than Kenneth. Kenneth has 544 soccer cards. How many soccer cards does Luis have?

544 -199 = ?      ,   ? + 199 =544