Identify the words that have multiple meanings and are stumping your students. You cannot teach kids all the words that have multiple meanings, so don't even try. Instead identify those that they are specifically struggling with, or those that you feel are most important for them to understand. Use a dictionary to try and identify some of those words.
Write the words on index cards. Write one word per card, making sure to only write the word on one side of the index card. Write the words in big, bold letters in the middle of the card in order to ensure their visibility.
Write the different meanings of the word on the opposite side of the index card. Make sure that the definitions are clear. Use examples. It is not enough to have the meaning of words, put them into context. Make sentences as examples that your students will be able to identify with.
Make it fun. Words are important. They convey a lot of meaning, but colors and pictures also help convey emotion and keep learning fun. If your students are having fun learning, they will be more likely to remember what they've learned.
Shuffle the cards and read them to your students. Pass them around the classroom and have them read them to each other. Put the students into groups and and have them discuss the words and their meanings. Let them try and come up with their own examples for the meanings of the words. It doesn't matter how you do it, just make sure you keep it fun.
Quiz the students. It is always important that you assess how well your students were able to learn what you've taught them. Remember to keep this part of the learning process fun as well. Let them get involved. Have a group quiz where those who answer correctly earn points and/or prizes.