We just checked your page opendatakit.org for known problems and our crawler found 666 issues problems.
These are amongst others:
Alt Attribute not set All of these pictures do not use the alt-attribute. This attribute helps Google to understand what an image is about.
Show errors Empty Meta-Description Google may use the meta-description tag to construct the snippets that they show with your search result. By leaving this tag empty, you are giving away a powerful tool to catch a users interest in your site and increase your click-through-rate.