Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 766 · 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? Which of these is kept the same? (a) how dark the writing is (b) the kind of juice (c) the same paper
2. 2.🔮 Predict: the adult irons for only one second. What happens? (a) writing turns green (b) the paper floats (c) writing stays faint (d) it gets darker
3. 3.🍋 What colour does the lemon writing turn when an adult warms it? (a) brown (b) blue (c) green (d) white
4. 4.🔍 Which is the odd one out? (a) ironing the paper (b) putting the iron away (c) cutting the lemon (d) dipping the cotton bud
5. 5.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) turmeric powder (c) lemon juice (d) white paper
6. 6.True or false: a small bowl is needed for the secret lemon message. (a) False (b) True
7. 7.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the iron setting”? (a) we measure it (b) we keep it the same (c) we change it
8. 8.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the ironing time”? (a) we change it (b) we keep it the same (c) we measure it
9. 9.🍋 Secret message: who does this step — writing the message? (a) a child can do it (b) an adult does it
10. 10.⚖️ 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) False (b) True
11. 11.🍋 Which of these steps is a job for an adult? (a) putting the iron away (b) writing the message (c) letting the paper dry (d) reading the message
12. 12.🧺 Which of these is needed for the secret lemon message? (a) a cotton bud (b) yeast (c) a mirror (d) a balloon
13. 13.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) a balloon (c) an adult with an iron (d) a battery cell
14. 14.⚖️ 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) how dark the writing is (c) the same paper (d) the kind of juice
15. 15.🧺 Do we need white paper for the secret lemon message? (a) needed (b) not needed
16. 16.🔍 Which is the odd one out? (a) letting the paper dry (b) plugging in the iron (c) cutting the lemon (d) ironing the paper
17. 17.🛟 Why must children keep their fingers away from the iron? (a) it is sticky (b) it can burn skin (c) it is cold (d) it is magnetic
18. 18.🍋 Secret message: who does this step — reading the message? (a) an adult does it (b) a child can do it
19. 19.🧺 Do we need lemon juice for the secret lemon message? (a) needed (b) not needed
20. 20.⚖️ 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 same cotton bud (c) the kind of juice
21. 21.🍋 Secret message: who does this step — cutting the lemon? (a) a child can do it (b) an adult does it
22. 22.🧺 Do we need a magnet for the secret lemon message? (a) not needed (b) needed
23. 23.True or false: a cotton bud is not needed for the secret lemon message. (a) False (b) True
24. 24.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) putting the iron away (c) plugging in the iron (d) dipping the cotton bud
25. 25.True or false: plugging in the iron is a job for an adult. (a) False (b) True
26. 26.🧺 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
27. 27.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) plugging in the iron (c) letting the paper dry (d) putting the iron away
28. 28.⚖️ 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
29. 29.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: how dark the writing is is what we measure. (a) False (b) True
30. 30.🍋 Which of these steps is a job a child can do? (a) cutting the lemon (b) reading the message (c) plugging in the iron (d) putting the iron away
31. 31.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) a small bowl (c) yeast (d) lemon juice
32. 32.True or false: lemon juice is not needed for the secret lemon message. (a) True (b) False
33. 33.🧺 Do we need a cotton bud for the secret lemon message? (a) needed (b) not needed
34. 34.🍋 Which of these steps is a job for an adult? (a) writing the message (b) letting the paper dry (c) ironing the paper (d) dipping the cotton bud
35. 35.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) cutting the lemon (c) dipping the cotton bud (d) reading the message
36. 36.🔮 Can the brown writing go back to being invisible? (a) yes, if cooled (b) no, it stays brown (c) yes, in the dark (d) yes, if shaken
37. 37.True or false: putting the iron away is a job for an adult. (a) True (b) False
38. 38.True or false: a cotton bud is needed for the secret lemon message. (a) True (b) False
39. 39.🔍 Which is the odd one out? (a) letting the paper dry (b) writing the message (c) cutting the lemon (d) reading the message
40. 40.True or false: letting the paper dry is a job a child can do. (a) True (b) False

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