Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 834 · 40 questions

What you do (Heat shows the secret): 1. Dip a cotton bud in lemon juice and write a secret message on white paper. 2. Let the paper dry completely — the writing disappears. 3. An adult irons the paper on a low setting while you watch from a safe distance. 4. Read the brown message and wash your hands.

1. 1.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) yeast (c) turmeric powder (d) white paper
2. 2.🧺 Do we need a battery cell for the secret lemon message? (a) needed (b) not needed
3. 3.🧺 Do we need an adult with an iron for the secret lemon message? (a) needed (b) not needed
4. 4.🍋 Why can’t you see the lemon writing once it dries? (a) the ink is magnetic (b) the paper ate it (c) it turned into air (d) dry juice is see-through
5. 5.True or false: a battery cell is needed for the secret lemon message. (a) False (b) True
6. 6.🍋 Which of these steps is a job for an adult? (a) ironing the paper (b) letting the paper dry (c) reading the message (d) writing the message
7. 7.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a cotton bud (c) a small bowl (d) a battery cell
8. 8.🔍 Which is the odd one out? (a) dipping the cotton bud (b) cutting the lemon (c) ironing the paper (d) putting the iron away
9. 9.True or false: a magnet is needed for the secret lemon message. (a) False (b) True
10. 10.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is what we measure. (a) True (b) False
11. 11.🧺 Do we need white paper for the secret lemon message? (a) needed (b) not needed
12. 12.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) a small bowl (c) a magnet (d) lemon juice
13. 13.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) blue words (b) a rainbow (c) almost nothing (d) dark brown words
14. 14.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) a small bowl (c) a mirror (d) a magnet
15. 15.🧺 Do we need a balloon for the secret lemon message? (a) needed (b) not needed
16. 16.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is what we measure. (a) True (b) False
17. 17.🔍 Which is the odd one out? (a) ironing the paper (b) cutting the lemon (c) writing the message (d) putting the iron away
18. 18.True or false: reading the message is a job for an adult. (a) True (b) False
19. 19.True or false: a cotton bud is not needed for the secret lemon message. (a) False (b) True
20. 20.🍋 Secret message: who does this step — reading the message? (a) an adult does it (b) a child can do it
21. 21.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the same cotton bud (b) the kind of juice (c) the ironing time (d) how dark the writing is
22. 22.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is kept the same. (a) False (b) True
23. 23.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) yeast (b) lemon juice (c) an adult with an iron (d) a cotton bud
24. 24.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) wash your hands (b) rub your eyes (c) skip washing (d) lick your fingers
25. 25.🛟 Who should use the hot iron in the secret message experiment? (a) any child (b) only an adult (c) the youngest child (d) whoever is fastest
26. 26.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same cotton bud”? (a) we measure it (b) we keep it the same (c) we change it
27. 27.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same paper”? (a) we change it (b) we measure it (c) we keep it the same
28. 28.True or false: reading the message is a job a child can do. (a) False (b) True
29. 29.🧺 Do we need a mirror for the secret lemon message? (a) needed (b) not needed
30. 30.🧺 Do we need turmeric powder for the secret lemon message? (a) not needed (b) needed
31. 31.🍋 What colour does the lemon writing turn when an adult warms it? (a) blue (b) green (c) brown (d) white
32. 32.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a balloon (b) a small bowl (c) a cotton bud (d) lemon juice
33. 33.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) how dark the writing is (b) the kind of juice (c) the iron setting
34. 34.🔍 Which is the odd one out? (a) dipping the cotton bud (b) letting the paper dry (c) cutting the lemon (d) reading the message
35. 35.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) writing the message (c) putting the iron away (d) letting the paper dry
36. 36.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the kind of juice (b) the ironing time (c) how dark the writing is
37. 37.🔮 Can the brown writing go back to being invisible? (a) yes, if cooled (b) yes, in the dark (c) yes, if shaken (d) no, it stays brown
38. 38.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the kind of juice”? (a) we change it (b) we measure it (c) we keep it the same
39. 39.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the ironing time (b) the same paper (c) the kind of juice (d) the same cotton bud
40. 40.🍋 Secret message: who does this step — dipping the cotton bud? (a) an adult does it (b) a child can do it

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