diff --git a/theatre/core/src/sequences/Sequence.ts b/theatre/core/src/sequences/Sequence.ts
index b0c42b6..c227047 100644
--- a/theatre/core/src/sequences/Sequence.ts
+++ b/theatre/core/src/sequences/Sequence.ts
@@ -118,7 +118,7 @@ export default class Sequence {
     return this._lengthD.getValue()
   }
 
-  get positionDerivation() {
+  get positionPrism() {
     return this._positionD
   }
 
diff --git a/theatre/core/src/sheetObjects/SheetObject.ts b/theatre/core/src/sheetObjects/SheetObject.ts
index d927f09..ee21417 100644
--- a/theatre/core/src/sheetObjects/SheetObject.ts
+++ b/theatre/core/src/sheetObjects/SheetObject.ts
@@ -253,7 +253,7 @@ export default class SheetObject implements IdentityPrismProvider {
             const interpolate =
               propConfig.interpolate! as Interpolator<$IntentionalAny>
 
-            const updateSequenceValueFromItsDerivation = () => {
+            const updateSequenceValueFromItsPrism = () => {
               const triple = pr.getValue()
 
               if (!triple) return valsAtom.setIn(pathToProp, undefined)
@@ -279,9 +279,9 @@ export default class SheetObject implements IdentityPrismProvider {
                 interpolate(left, right, triple.progression),
               )
             }
-            const untap = pr.onStale(updateSequenceValueFromItsDerivation)
+            const untap = pr.onStale(updateSequenceValueFromItsPrism)
 
-            updateSequenceValueFromItsDerivation()
+            updateSequenceValueFromItsPrism()
             untaps.push(untap)
           }
           return () => {
@@ -304,7 +304,7 @@ export default class SheetObject implements IdentityPrismProvider {
       this.template.project.pointers.historic.sheetsById[this.address.sheetId]
         .sequence.tracksByObject[this.address.objectKey].trackData[trackId]
 
-    const timeD = this.sheet.getSequence().positionDerivation
+    const timeD = this.sheet.getSequence().positionPrism
 
     return interpolationTripleAtPosition(this._internalUtilCtx, trackP, timeD)
   }
diff --git a/theatre/core/src/sheetObjects/SheetObjectTemplate.ts b/theatre/core/src/sheetObjects/SheetObjectTemplate.ts
index abe5a63..61c530c 100644
--- a/theatre/core/src/sheetObjects/SheetObjectTemplate.ts
+++ b/theatre/core/src/sheetObjects/SheetObjectTemplate.ts
@@ -128,7 +128,7 @@ export default class SheetObjectTemplate {
    * Returns values that are set statically (ie, not sequenced, and not defaults)
    */
   getStaticValues(): Prism<SerializableMap> {
-    return this._cache.get('getDerivationOfStatics', () =>
+    return this._cache.get('getStaticValues', () =>
       prism(() => {
         const pointerToSheetState =
           this.sheetTemplate.project.pointers.historic.sheetsById[
diff --git a/theatre/core/src/sheetObjects/TheatreSheetObject.ts b/theatre/core/src/sheetObjects/TheatreSheetObject.ts
index 91659c2..478fe6d 100644
--- a/theatre/core/src/sheetObjects/TheatreSheetObject.ts
+++ b/theatre/core/src/sheetObjects/TheatreSheetObject.ts
@@ -148,7 +148,7 @@ export default class TheatreSheetObject<
   }
 
   private _valuesPrism(): Prism<this['value']> {
-    return this._cache.get('onValuesChangeDerivation', () => {
+    return this._cache.get('_valuesPrism', () => {
       const sheetObject = privateAPI(this)
       const d: Prism<PropsValue<Props>> = prism(() => {
         return val(sheetObject.getValues().getValue()) as $FixMe
diff --git a/theatre/studio/src/TheatreStudio.ts b/theatre/studio/src/TheatreStudio.ts
index cb38e8b..7dc56e5 100644
--- a/theatre/studio/src/TheatreStudio.ts
+++ b/theatre/studio/src/TheatreStudio.ts
@@ -410,8 +410,8 @@ export default class TheatreStudio implements IStudio {
     })
   }
 
-  private _getSelectionDerivation(): Prism<(ISheetObject | ISheet)[]> {
-    return this._cache.get('_getStateDerivation()', () =>
+  private _getSelectionPrism(): Prism<(ISheetObject | ISheet)[]> {
+    return this._cache.get('_getSelectionPrism()', () =>
       prism((): (ISheetObject | ISheet)[] => {
         return getOutlineSelection()
           .filter(
@@ -424,7 +424,7 @@ export default class TheatreStudio implements IStudio {
   }
 
   private _getSelection(): (ISheetObject | ISheet)[] {
-    return this._getSelectionDerivation().getValue()
+    return this._getSelectionPrism().getValue()
   }
 
   setSelection(selection: Array<ISheetObject | ISheet>): void {
@@ -440,7 +440,7 @@ export default class TheatreStudio implements IStudio {
   }
 
   onSelectionChange(fn: (s: (ISheetObject | ISheet)[]) => void): VoidFn {
-    return this._getSelectionDerivation().onChange(studioTicker, fn, true)
+    return this._getSelectionPrism().onChange(studioTicker, fn, true)
   }
 
   get selection(): Array<ISheetObject | ISheet> {
diff --git a/theatre/studio/src/panels/SequenceEditorPanel/RightOverlay/Playhead.tsx b/theatre/studio/src/panels/SequenceEditorPanel/RightOverlay/Playhead.tsx
index b19ac57..4916d15 100644
--- a/theatre/studio/src/panels/SequenceEditorPanel/RightOverlay/Playhead.tsx
+++ b/theatre/studio/src/panels/SequenceEditorPanel/RightOverlay/Playhead.tsx
@@ -265,7 +265,7 @@ const Playhead: React.FC<{layoutP: Pointer<SequenceEditorPanelLayout>}> = ({
       getIsPlayheadAttachedToFocusRange(sequence),
     )
 
-    const posInUnitSpace = sequence.positionDerivation.getValue()
+    const posInUnitSpace = sequence.positionPrism.getValue()
 
     const posInClippedSpace = val(layoutP.clippedSpace.fromUnitSpace)(
       posInUnitSpace,
diff --git a/theatre/studio/src/propEditors/useEditingToolsForCompoundProp.tsx b/theatre/studio/src/propEditors/useEditingToolsForCompoundProp.tsx
index e1c8f28..4de5cf3 100644
--- a/theatre/studio/src/propEditors/useEditingToolsForCompoundProp.tsx
+++ b/theatre/studio/src/propEditors/useEditingToolsForCompoundProp.tsx
@@ -235,7 +235,7 @@ function ControlIndicators({
   return usePrism(() => {
     const pathToProp = getPointerParts(pointerToProp).path
 
-    const sequencePosition = val(obj.sheet.getSequence().positionDerivation)
+    const sequencePosition = val(obj.sheet.getSequence().positionPrism)
 
     /*
     2/10 perf concern:
diff --git a/theatre/studio/src/propEditors/useEditingToolsForSimpleProp.tsx b/theatre/studio/src/propEditors/useEditingToolsForSimpleProp.tsx
index 5882278..0c1241a 100644
--- a/theatre/studio/src/propEditors/useEditingToolsForSimpleProp.tsx
+++ b/theatre/studio/src/propEditors/useEditingToolsForSimpleProp.tsx
@@ -65,7 +65,7 @@ const cache = new WeakMap<{}, Prism<EditingTools<$IntentionalAny>>>()
  * Note: we're able to get `obj` and `propConfig` from `pointerToProp`,
  * so the only reason they're still in the arguments list is that
  */
-function createDerivation<T extends SerializablePrimitive>(
+function createPrism<T extends SerializablePrimitive>(
   pointerToProp: Pointer<T>,
   obj: SheetObject,
   propConfig: PropTypeConfig_AllSimples,
@@ -181,9 +181,7 @@ function createDerivation<T extends SerializablePrimitive>(
                 sequenceTrackId
               ],
             )
-            const sequencePosition = val(
-              obj.sheet.getSequence().positionDerivation,
-            )
+            const sequencePosition = val(obj.sheet.getSequence().positionPrism)
             return getNearbyKeyframesOfTrack(
               obj,
               track && {
@@ -325,7 +323,7 @@ function createDerivation<T extends SerializablePrimitive>(
   })
 }
 
-function getDerivation<T extends SerializablePrimitive>(
+function getPrism<T extends SerializablePrimitive>(
   pointerToProp: Pointer<T>,
   obj: SheetObject,
   propConfig: PropTypeConfig_AllSimples,
@@ -333,7 +331,7 @@ function getDerivation<T extends SerializablePrimitive>(
   if (cache.has(pointerToProp)) {
     return cache.get(pointerToProp)!
   } else {
-    const d = createDerivation(pointerToProp, obj, propConfig)
+    const d = createPrism(pointerToProp, obj, propConfig)
     cache.set(pointerToProp, d)
     return d
   }
@@ -354,7 +352,7 @@ export function useEditingToolsForSimplePropInDetailsPanel<
   obj: SheetObject,
   propConfig: PropTypeConfig_AllSimples,
 ): EditingTools<T> {
-  const der = getDerivation(pointerToProp, obj, propConfig)
+  const der = getPrism(pointerToProp, obj, propConfig)
   return usePrismInstance(der)
 }