Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 842 · 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.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) a balloon (c) a small bowl (d) an adult with an iron
2. 2.🔍 Which is the odd one out? (a) putting the iron away (b) ironing the paper (c) plugging in the iron (d) dipping the cotton bud
3. 3.⚖️ 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 change it (c) we measure it
4. 4.🍋 Secret message: who does this step — letting the paper dry? (a) a child can do it (b) an adult does it
5. 5.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a mirror (b) lemon juice (c) a small bowl (d) a cotton bud
6. 6.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) plugging in the iron (c) cutting the lemon (d) letting the paper dry
7. 7.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is kept the same. (a) False (b) True
8. 8.🧺 Do we need a magnet for the secret lemon message? (a) needed (b) not needed
9. 9.🔍 Which is the odd one out? (a) cutting the lemon (b) dipping the cotton bud (c) letting the paper dry (d) reading the message
10. 10.🍋 Which of these steps is a job for an adult? (a) reading the message (b) dipping the cotton bud (c) putting the iron away (d) writing the message
11. 11.🍋 Which of these steps is a job a child can do? (a) reading the message (b) cutting the lemon (c) ironing the paper (d) putting the iron away
12. 12.🧺 Do we need white paper for the secret lemon message? (a) needed (b) not needed
13. 13.🧺 Do we need turmeric powder for the secret lemon message? (a) needed (b) not needed
14. 14.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) an adult with an iron (c) yeast (d) white paper
15. 15.🔮 Predict: the adult irons for only one second. What happens? (a) writing turns green (b) it gets darker (c) writing stays faint (d) the paper floats
16. 16.⚖️ 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
17. 17.🍋 Secret message: who does this step — putting the iron away? (a) an adult does it (b) a child can do it
18. 18.⚖️ 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 iron setting (c) the same cotton bud (d) the kind of juice
19. 19.🍋 Secret message: who does this step — writing the message? (a) a child can do it (b) an adult does it
20. 20.🧺 Do we need a mirror for the secret lemon message? (a) needed (b) not needed
21. 21.🍋 Why does the lemon writing turn brown with heat? (a) the iron is brown (b) heat adds colour (c) paper turns lemony (d) the juice scorches first
22. 22.🧺 Do we need a cotton bud for the secret lemon message? (a) not needed (b) needed
23. 23.🧺 Which of these is needed for the secret lemon message? (a) a mirror (b) a small bowl (c) a magnet (d) a balloon
24. 24.True or false: putting the iron away is a job a child can do. (a) False (b) True
25. 25.🍋 Which of these steps is a job for an adult? (a) reading the message (b) cutting the lemon (c) writing the message (d) dipping the cotton bud
26. 26.🛟 Who should use the hot iron in the secret message experiment? (a) whoever is fastest (b) any child (c) the youngest child (d) only an adult
27. 27.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a cotton bud (c) white paper (d) turmeric powder
28. 28.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is kept the same. (a) True (b) False
29. 29.🧺 Which of these is not needed for the secret lemon message? (a) an adult with an iron (b) a small bowl (c) a cotton bud (d) a battery cell
30. 30.⚖️ 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
31. 31.🍋 Secret message: who does this step — dipping the cotton bud? (a) an adult does it (b) a child can do it
32. 32.True or false: dipping the cotton bud is a job for an adult. (a) False (b) True
33. 33.⚖️ 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) True (b) False
34. 34.True or false: turmeric powder is not needed for the secret lemon message. (a) False (b) True
35. 35.📘 The browning of lemon juice with heat is a ___ change. (a) physical (b) magnetic (c) musical (d) chemical
36. 36.🔮 Can the brown writing go back to being invisible? (a) yes, if cooled (b) yes, if shaken (c) yes, in the dark (d) no, it stays brown
37. 37.⚖️ 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
38. 38.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) wash your hands (b) skip washing (c) lick your fingers (d) rub your eyes
39. 39.True or false: a magnet is not needed for the secret lemon message. (a) True (b) False
40. 40.True or false: writing the message is a job a child can do. (a) True (b) False

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