Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 230 · 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.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same paper”? (a) we measure it (b) we keep it the same (c) we change it
2. 2.True or false: writing the message is a job for an adult. (a) False (b) True
3. 3.🍋 Secret message: who does this step — dipping the cotton bud? (a) an adult does it (b) a child can do it
4. 4.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) turmeric powder (c) lemon juice (d) a battery cell
5. 5.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) dark brown words (b) blue words (c) almost nothing (d) a rainbow
6. 6.🛟 Why must children keep their fingers away from the iron? (a) it is magnetic (b) it is cold (c) it is sticky (d) it can burn skin
7. 7.🧺 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) lemon juice (d) a mirror
8. 8.🛟 Who should use the hot iron in the secret message experiment? (a) whoever is fastest (b) only an adult (c) any child (d) the youngest child
9. 9.🧺 Do we need an adult with an iron for the secret lemon message? (a) needed (b) not needed
10. 10.True or false: a mirror is needed for the secret lemon message. (a) False (b) True
11. 11.True or false: turmeric powder is not needed for the secret lemon message. (a) False (b) True
12. 12.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) writing the message (c) reading the message (d) ironing the paper
13. 13.🍋 Secret message: who does this step — letting the paper dry? (a) a child can do it (b) an adult does it
14. 14.🍋 Secret message: who does this step — writing the message? (a) a child can do it (b) an adult does it
15. 15.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) skip washing (b) lick your fingers (c) rub your eyes (d) wash your hands
16. 16.⚖️ 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
17. 17.🧺 Do we need white paper for the secret lemon message? (a) not needed (b) needed
18. 18.True or false: dipping the cotton bud is a job a child can do. (a) True (b) False
19. 19.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) how dark the writing is (b) the same cotton bud (c) the kind of juice (d) the iron setting
20. 20.True or false: turmeric powder is needed for the secret lemon message. (a) False (b) True
21. 21.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is the one thing we change. (a) True (b) False
22. 22.🍋 Secret message: who does this step — cutting the lemon? (a) a child can do it (b) an adult does it
23. 23.🔮 Can the brown writing go back to being invisible? (a) no, it stays brown (b) yes, if cooled (c) yes, if shaken (d) yes, in the dark
24. 24.🔍 Which is the odd one out? (a) ironing the paper (b) plugging in the iron (c) reading the message (d) cutting the lemon
25. 25.🧺 Which of these is not needed for the secret lemon message? (a) a magnet (b) lemon juice (c) a cotton bud (d) white paper
26. 26.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) turmeric powder (b) a cotton bud (c) an adult with an iron (d) lemon juice
27. 27.🧺 Do we need a small bowl for the secret lemon message? (a) needed (b) not needed
28. 28.⚖️ 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) how dark the writing is (c) the same cotton bud
29. 29.📘 The browning of lemon juice with heat is a ___ change. (a) chemical (b) musical (c) magnetic (d) physical
30. 30.True or false: cutting the lemon is a job a child can do. (a) True (b) False
31. 31.True or false: a small bowl is needed for the secret lemon message. (a) True (b) False
32. 32.🍋 Why can’t you see the lemon writing once it dries? (a) it turned into air (b) dry juice is see-through (c) the ink is magnetic (d) the paper ate it
33. 33.🔮 Predict: the adult irons for only one second. What happens? (a) the paper floats (b) writing turns green (c) writing stays faint (d) it gets darker
34. 34.True or false: white paper is not needed for the secret lemon message. (a) True (b) False
35. 35.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) yeast (b) white paper (c) lemon juice (d) a cotton bud
36. 36.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a small bowl (c) a battery cell (d) a cotton bud
37. 37.True or false: lemon juice is not needed for the secret lemon message. (a) True (b) False
38. 38.🍋 Secret message: who does this step — putting the iron away? (a) a child can do it (b) an adult does it
39. 39.🧺 Which of these is needed for the secret lemon message? (a) a battery cell (b) a cotton bud (c) turmeric powder (d) a balloon
40. 40.🍋 Which of these steps is a job a child can do? (a) writing the message (b) plugging in the iron (c) ironing the paper (d) putting the iron away

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