Design the lesson to be concrete. Provide objects that the children can touch and compare. For example, explaining how a clock works, bring in a clock that the children can pass around. Seeing the hands move can help them understand change over time better.
Stretch the lesson out over time. For example, you might have the children plant a bean in soil. Take a picture of the plant's progress every other day and label the day. This will allow you to see and talk about how the plant has changed, as well as the effect time has on the change.
Make the lessons personal. Ask the children to bring in baby pictures of themselves. Discuss how old they are, what that age means and how they've changed personally throughout that time. Talk about toys they once played with but don't now, and why that changed.
Look ahead. Talk with the children about what will happen next year. For example, you can have a conversation about the fact that they will learn things, but that it will take time. The information won't just "pop" into their head.