When Boo was about 3.5 months old I put her in a high chair for the first time. She loved being able to sit upright while exploring her toys from a new perspective. We took all the toys off and just put water onto the high chair tray, too...and she loved splishing and splashing in the little bit of water. She ran her fingers through it and over it. Tried to taste it. Grab it. Push it over and off. I love the simplicity of good play. Sometimes you really don't need much. Just imagination and a mind for exploring and discovering - little ones are hardwired with everything required.