Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 591 · 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.True or false: ironing the paper is a job a child can do. (a) False (b) True
2. 2.⚖️ 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
3. 3.🧺 Which of these is needed for the secret lemon message? (a) a mirror (b) turmeric powder (c) an adult with an iron (d) a magnet
4. 4.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) yeast (b) white paper (c) a small bowl (d) a cotton bud
5. 5.🧺 Do we need a balloon for the secret lemon message? (a) needed (b) not needed
6. 6.True or false: writing the message 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 iron setting”? (a) we keep it the same (b) we change it (c) we measure it
8. 8.🍋 Secret message: who does this step — plugging in the iron? (a) an adult does it (b) a child can do it
9. 9.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) lick your fingers (b) wash your hands (c) skip washing (d) rub your eyes
10. 10.🧺 Do we need lemon juice for the secret lemon message? (a) needed (b) not needed
11. 11.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) almost nothing (b) dark brown words (c) blue words (d) a rainbow
12. 12.True or false: white paper is not needed for the secret lemon message. (a) False (b) True
13. 13.🧺 Do we need a small bowl for the secret lemon message? (a) needed (b) not needed
14. 14.🔍 Which is the odd one out? (a) dipping the cotton bud (b) letting the paper dry (c) putting the iron away (d) writing the message
15. 15.🧺 Do we need an adult with an iron for the secret lemon message? (a) not needed (b) needed
16. 16.🍋 Which of these steps is a job a child can do? (a) plugging in the iron (b) ironing the paper (c) putting the iron away (d) letting the paper dry
17. 17.⚖️ 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 keep it the same (c) we measure it
18. 18.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is kept the same. (a) False (b) True
19. 19.🔮 Can the brown writing go back to being invisible? (a) yes, if cooled (b) no, it stays brown (c) yes, if shaken (d) yes, in the dark
20. 20.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) dipping the cotton bud (c) reading the message (d) cutting the lemon
21. 21.🧺 Do we need turmeric powder for the secret lemon message? (a) needed (b) not needed
22. 22.🍋 Secret message: who does this step — letting the paper dry? (a) an adult does it (b) a child can do it
23. 23.⚖️ 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
24. 24.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) white paper (c) a cotton bud (d) a magnet
25. 25.🍋 Secret message: who does this step — reading the message? (a) an adult does it (b) a child can do it
26. 26.🛟 Who should use the hot iron in the secret message experiment? (a) whoever is fastest (b) the youngest child (c) only an adult (d) any child
27. 27.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is kept the same. (a) True (b) False
28. 28.🔮 Predict: the adult irons for only one second. What happens? (a) it gets darker (b) writing turns green (c) writing stays faint (d) the paper floats
29. 29.⚖️ 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
30. 30.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) lemon juice (c) a mirror (d) turmeric powder
31. 31.🔍 Which is the odd one out? (a) cutting the lemon (b) plugging in the iron (c) ironing the paper (d) letting the paper dry
32. 32.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) an adult with an iron (c) turmeric powder (d) a cotton bud
33. 33.🧺 Which of these is needed for the secret lemon message? (a) turmeric powder (b) a cotton bud (c) a magnet (d) a battery cell
34. 34.True or false: a small bowl is needed for the secret lemon message. (a) False (b) True
35. 35.📘 The browning of lemon juice with heat is a ___ change. (a) magnetic (b) physical (c) chemical (d) musical
36. 36.🍋 Secret message: who does this step — writing the message? (a) a child can do it (b) an adult does it
37. 37.True or false: white paper is needed for the secret lemon message. (a) False (b) True
38. 38.🔍 Which is the odd one out? (a) dipping the cotton bud (b) putting the iron away (c) plugging in the iron (d) cutting the lemon
39. 39.🍋 Which of these steps is a job for an adult? (a) reading the message (b) ironing the paper (c) writing the message (d) letting the paper dry
40. 40.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the iron setting (b) the kind of juice (c) the same cotton bud (d) how dark the writing is

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