Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 473 · 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.🧺 Which of these is needed for the secret lemon message? (a) yeast (b) a balloon (c) an adult with an iron (d) turmeric powder
2. 2.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “how dark the writing is”? (a) we measure it (b) we keep it the same (c) we change it
3. 3.True or false: putting the iron away is a job a child can do. (a) True (b) False
4. 4.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a small bowl (c) a magnet (d) white paper
5. 5.🔍 Which is the odd one out? (a) dipping the cotton bud (b) reading the message (c) plugging in the iron (d) letting the paper dry
6. 6.🧺 Do we need an adult with an iron for the secret lemon message? (a) not needed (b) needed
7. 7.🔮 Predict: the adult irons for only one second. What happens? (a) writing turns green (b) the paper floats (c) it gets darker (d) writing stays faint
8. 8.🔮 Can the brown writing go back to being invisible? (a) yes, in the dark (b) no, it stays brown (c) yes, if cooled (d) yes, if shaken
9. 9.🍋 Why does the lemon writing turn brown with heat? (a) the juice scorches first (b) heat adds colour (c) the iron is brown (d) paper turns lemony
10. 10.🧺 Which of these is not needed for the secret lemon message? (a) an adult with an iron (b) white paper (c) lemon juice (d) yeast
11. 11.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is what we measure. (a) False (b) True
12. 12.🧺 Do we need a small bowl for the secret lemon message? (a) not needed (b) needed
13. 13.📘 The browning of lemon juice with heat is a ___ change. (a) chemical (b) musical (c) physical (d) magnetic
14. 14.⚖️ 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
15. 15.🛟 Why must children keep their fingers away from the iron? (a) it is sticky (b) it is cold (c) it is magnetic (d) it can burn skin
16. 16.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is kept the same. (a) False (b) True
17. 17.🧺 Do we need lemon juice for the secret lemon message? (a) not needed (b) needed
18. 18.🧺 Do we need white paper for the secret lemon message? (a) needed (b) not needed
19. 19.🧺 Which of these is needed for the secret lemon message? (a) yeast (b) a cotton bud (c) a magnet (d) a balloon
20. 20.⚖️ 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 iron setting (d) the same cotton bud
21. 21.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) skip washing (b) lick your fingers (c) wash your hands (d) rub your eyes
22. 22.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a battery cell (b) a cotton bud (c) white paper (d) lemon juice
23. 23.True or false: lemon juice is needed for the secret lemon message. (a) False (b) True
24. 24.🧺 Which of these is not needed for the secret lemon message? (a) a cotton bud (b) lemon juice (c) a small bowl (d) a balloon
25. 25.🍋 Which of these steps is a job for an adult? (a) plugging in the iron (b) dipping the cotton bud (c) writing the message (d) reading the message
26. 26.🍋 Which of these steps is a job for an adult? (a) writing the message (b) dipping the cotton bud (c) reading the message (d) cutting the lemon
27. 27.🧺 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) white paper (d) turmeric powder
28. 28.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) white paper (c) a mirror (d) a small bowl
29. 29.🧺 Do we need a mirror for the secret lemon message? (a) needed (b) not needed
30. 30.True or false: an adult with an iron is needed for the secret lemon message. (a) False (b) True
31. 31.True or false: ironing the paper is a job a child can do. (a) True (b) False
32. 32.🔍 Which is the odd one out? (a) cutting the lemon (b) plugging in the iron (c) ironing the paper (d) reading the message
33. 33.🍋 What colour does the lemon writing turn when an adult warms it? (a) brown (b) green (c) white (d) blue
34. 34.🧺 Which of these is not needed for the secret lemon message? (a) an adult with an iron (b) a cotton bud (c) a magnet (d) lemon juice
35. 35.🔍 Which is the odd one out? (a) putting the iron away (b) plugging in the iron (c) cutting the lemon (d) letting the paper dry
36. 36.⚖️ 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
37. 37.True or false: a magnet is not needed for the secret lemon message. (a) False (b) True
38. 38.True or false: a cotton bud is needed for the secret lemon message. (a) True (b) False
39. 39.🧺 Do we need turmeric powder for the secret lemon message? (a) needed (b) not needed
40. 40.⚖️ 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) True (b) False

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