Calculator Go Froms

Years 2 - 6

Summary

Choose a start and finish number on the chart and mark a 5 step pathway between them. Now teach the calculator to follow your path. Easy to state and easy to start, but lots of ways to do it. The more the children explore, the more they discover patterns in the chart. Suitable for threading.

Materials

Note

Thanks to Lisa Harris and Natalie Currie who have contributed experiences from trialling Calculator Go Froms. Please contact Doug. Williams, doug@blackdouglas.com.au, if you can enrich the activity further with your stories.

Procedure

  1. Person A selects any number as the Start and draws a ring around it.
  2. Person B chooses a Finish number and draws a ring in the same way.
  3. Person A now draws a path with four to six steps from the start to the finish. Steps are shown by arrows, for example:
Number Board 2
  

Content

  • addition facts beyond 10
  • addition facts to 10
  • equations: creating/solving
  • number line - ordering, operations
  • operations - whole number
  • pattern generalisation
  • pattern interpretation
  • pattern recognition
  • recording - calculator
  • recording - written
  • subtraction

  1. Person B has to enter the Start number into the calculator, then 'teach' it to follow the path. In this case:

    12 + 3 + 10 + 9 - 3 = 31

    Note: Any numbers can be chosen for the steps, the path doesn't have to be 'tight' like the one shown.
  2. Both players record the calculator steps.
  3. Swap roles and Person B uses a different colour to mark a path for Person A to teach the calculator.
  4. When players have completed, say, two paths each they predict and write the backwards path for each one and check it with the calculator. In the case above this is:

    31 + 3 - 9 - 10 - 3 = 12

Lisa Harris & Natalie Currie assessed Calculator Go Froms in this way after trialling in their class at St. Vincent's School, Aranda, ACT as part of their six day professional development course Working Like A Mathematician, organised by the Catholic Diocese of Canberra Goulburn.

Grace is in Year 3. Click her image and she will explain Calculator Go Froms.

Extensions

  1. Create two other pathways to Go From the Start number to the Finish number.
  2. What happens if the path must always be steps of the same size? Can you still make a path from your Start to your Finish number?
  3. I am thinking of a Start number. I am not going to tell you what it is, but I will tell you the calculator path from it to the Finish. Find my Start number. The path is:

    ? + 12 - 1 - 10 = 17

  4. Use the special charts Before Zero and After 99. Ask the children to complete the charts first then try the activity, but either Start or Finish must be one of the numbers they added.
  5. Try the activity with your own chart. Ask children to cut their own square, say 8x8, from graph paper and create their own chart. Does it have to begin at zero? Does the pattern between the cells have to be adding one?
  6. Complement with the activity Pattern Boards and Maths300 Lesson 19, Backtracking.


Return to Calculating Changes Activities

Calculating Changes ... is a division of ... Mathematics Centre