This lesson first consists of base words ending in -de that change by dropping -de and adding -sion.  The second word sort consists of base words ending in -it that change by dropping -it and adding -ission.

Sort base words ending in -de under Base -de.

Sort words that changed -de to -sion under -de > sion.

Sort base words ending in -it under Base -it.

Sort words that change -it to -ission under -it > ission.

Categories:  Base -de            -de > sion           Base -it            -it > ission

explode - explosion - admit - admission - decide - invasion - omit - permission - submit - decision - conclusion - omission - protrude - invade - intrude - submission - protrusion - permit - intrusion - conclude - division  - allude - divide - allusion