Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 524 · 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.🧺 Do we need white paper for the secret lemon message? (a) not needed (b) needed
2. 2.📘 The browning of lemon juice with heat is a ___ change. (a) chemical (b) physical (c) magnetic (d) musical
3. 3.⚖️ 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
4. 4.🧺 Do we need yeast for the secret lemon message? (a) not needed (b) needed
5. 5.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) a small bowl (c) turmeric powder (d) lemon juice
6. 6.True or false: dipping the cotton bud is a job for an adult. (a) True (b) False
7. 7.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the ironing time”? (a) we measure it (b) we keep it the same (c) we change it
8. 8.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) reading the message (c) cutting the lemon (d) plugging in the iron
9. 9.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is kept the same. (a) False (b) True
10. 10.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) rub your eyes (b) lick your fingers (c) wash your hands (d) skip washing
11. 11.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “how dark the writing is”? (a) we change it (b) we keep it the same (c) we measure it
12. 12.🍋 Why can’t you see the lemon writing once it dries? (a) dry juice is see-through (b) it turned into air (c) the ink is magnetic (d) the paper ate it
13. 13.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is kept the same. (a) True (b) False
14. 14.True or false: a cotton bud is needed for the secret lemon message. (a) False (b) True
15. 15.🧺 Which of these is needed for the secret lemon message? (a) yeast (b) turmeric powder (c) a cotton bud (d) a balloon
16. 16.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the kind of juice (b) the ironing time (c) the same cotton bud (d) how dark the writing is
17. 17.🍋 Secret message: who does this step — putting the iron away? (a) a child can do it (b) an adult does it
18. 18.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) writing the message (c) plugging in the iron (d) letting the paper dry
19. 19.🍋 Which of these steps is a job a child can do? (a) writing the message (b) cutting the lemon (c) plugging in the iron (d) ironing the paper
20. 20.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) a cotton bud (c) a magnet (d) lemon juice
21. 21.🍋 Which of these steps is a job for an adult? (a) ironing the paper (b) reading the message (c) writing the message (d) letting the paper dry
22. 22.🔍 Which is the odd one out? (a) plugging in the iron (b) writing the message (c) ironing the paper (d) putting the iron away
23. 23.🔮 Can the brown writing go back to being invisible? (a) yes, if cooled (b) yes, if shaken (c) no, it stays brown (d) yes, in the dark
24. 24.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a balloon (b) an adult with an iron (c) a cotton bud (d) white paper
25. 25.🛟 Who should use the hot iron in the secret message experiment? (a) any child (b) only an adult (c) whoever is fastest (d) the youngest child
26. 26.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is what we measure. (a) False (b) True
27. 27.True or false: putting the iron away is a job for an adult. (a) False (b) True
28. 28.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) reading the message (c) cutting the lemon (d) dipping the cotton bud
29. 29.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) writing the message (c) putting the iron away (d) dipping the cotton bud
30. 30.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: how dark the writing is is kept the same. (a) False (b) True
31. 31.True or false: yeast is not needed for the secret lemon message. (a) False (b) True
32. 32.True or false: plugging in the iron is a job a child can do. (a) False (b) True
33. 33.🍋 Secret message: who does this step — reading the message? (a) an adult does it (b) a child can do it
34. 34.True or false: a small bowl is not needed for the secret lemon message. (a) False (b) True
35. 35.True or false: writing the message is a job a child can do. (a) False (b) True
36. 36.⚖️ 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 iron setting (c) the same paper (d) how dark the writing is
37. 37.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) a rainbow (b) dark brown words (c) almost nothing (d) blue words
38. 38.🧺 Which of these is not needed for the secret lemon message? (a) a mirror (b) lemon juice (c) a small bowl (d) an adult with an iron
39. 39.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) a small bowl (c) a battery cell (d) a balloon
40. 40.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the kind of juice”? (a) we keep it the same (b) we measure it (c) we change it

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