There are several different types of word problem that students may encounter. For each of the different types there can be further differences. For example, in word problems involving the change in amounts, the starting amount, or the final amount, or the amount of change itself can be unknown.
It is important that students learn to solve all these different types of problem as this will demonstrate a full understanding of the meaning of the addition and subtraction operations. Practice with lots of examples is needed but this should be done after starting with plenty of handson activities with concrete materials.
The table below shows examples of these different types of addition and subtraction problems. Note: The table is based on The Common Addition and Subtraction Situations in the Common Core Standards For Mathematics (P.88)
Add To  Three ducks are on a pond. Four more ducks land on the pond. How many ducks are there now? 
3 + 4 = 7 
Three ducks are floating on a pond. Some more ducks fly in and land beside them and now there are five ducks. How many ducks flew in? 
3 + _ = 7  
Some ducks are floating on a pond. Four more ducks land beside them and there are now seven ducks. How many ducks were on the pond before the four landed? 
_ + 4 = 7  
Take From  Seven candles were burning on a cake. Jake blew three of them out. How many were left burning? 
7  3 = 4 
Seven candles were burning on a cake. Jake blew some of them out to leave four burning. How many did he blow out? 
7  _ = 4  
There were some candles on a cake. Jake blew four of them out to leave three of them burning. How many candles were burning at the start? 
_  4 = 3  
Put Together/ Take Apart 
There are four red grapes and three white grapes in a bowl. How many grapes are in the bowl? 
4 + 3 = _ 
Seven grapes are in a bowl. Four are red and the rest are white. How many white grapes are in the bowl? 
4 + _ = 7 7  4 = _ 

Compare  Sam has three games and Jack has seven games. How many more games does Jack have? OR Sam has three games and Jack has seven games. How many fewer games does Sam have? 
3 + _ = 7 7  3 = _ 
Jack has four more games than Sam. Sam has three games. How many games does Jack have? OR Sam has four fewer games than Jack. Sam has three games. How many games does Jack have? 
3 + 4 = _ 4 + 3 = _ 

Jack has four more games than Sam. Jack has seven games. How many games does Sam have? OR Sam has four fewer games than Jack. Jack has seven games. How many games does Jack have? 
7  4 = _ _ + 4 = 7 
Being able to solve each type of problem described above requires students to master the vocabulary of addition and subtraction. e.g. how many in total, altogether, combined, more than, difference, how many are needed.
Solving word problems both relies on and develops reading and language skills. Be aware of your children's reading level and use the opportunity to build these skills as you work and discuss the problems. Help your children to identify and comprehend the key words and terms within a problem. The table below contains just a few examples.
how many  how much  left over 
still to go  together  combined 
both  add  additional 
sum  total  difference 
change  increase  decrease 
fewer  more  remaining 
less  spent  reduce 
Allow your children as much time and give support and encouragement to help them interpret the problem. Work with them to understand the problem and determine the arithmetic operation required so that it can be translated into an addition or subtraction equation.
Be precise when discussing problems and look out for problems that are poorly worded. For example, “Jack has 7 console games and Sam has 4 console games. How many do they have altogether?” would be better worded as “Jack has 7 console games and Sam has 4 console games. How many console games do they have altogether?”
Students look for verbal clues when solving word problems. “More” usually (but not always) suggests addition and “less” usually (but not always) suggests subtraction. Look out for problems where these words suggest the opposite of what they usually do. For example, “The Green Team had 14 players which was 2 more than the Red Team. How many players were on the Red Team.” Students who can interpret this as 14  2 = 12 are well on their way to understanding addition and subtraction.
The following is based on work by Anne Newman^{1} .
Errors that students make in word problems can be categorized under one of five types:
Asking students to do, or answer, the following helps identify which type of error they are making:
1. Newman, A 1977, ‘An analysis of sixthgrade pupils’ errors on written mathematical tasks’, Bulletin of the Victorian Institute of Educational Research, vol 39, pp 31–43.
The two worksheets below have lots of word problems. Work through them with your children and provide help with vocabulary when needed.