Children enjoy working with ICT and it also gives them an opportunity to express themselves. This helps to show their understanding of science.
With PowerPoint, or other similar presentation packages, allow children to use words, images and even sounds to enhance their presentation. If you have a digital camera, pictures of classroom investigations and results can be used to illustrate the presentation.
Depending on the children, consider setting boundaries as to how many slides the presentation should include. Possibly give guidance on its content if the ability range would find this useful. You may even consider producing a template presentation, if children require a more structured approach.
Avoid too many presentations of group work in one sitting. Spread them out. Possibly end each morning with one presentation using the interactive whiteboard.